118 elements are known to us and which 94 are naturally occurring
Que 2
What is Dobereiner's Traids
Ans
In 1817 scientist Dobereiner arrange the elements with similar properties into group
Identify some groups having three elements each so he called his group Traida
According to him
when three elements in a traid were written in order of increasing atomic masses atomic mass of the middle element was the average of atomic masses of other two elements
Que 3
What is Newland law of octaves
Ans
In 1866 John newland arrange the known elements in the order of increasing atomic
masses
He found that every eighth element has the similar properties to that of the first
He compare this to the octaves found in music therefore he called it the law of octaves
Que 4
How many elements were known at the time of mendeleev classification of periodic table
Ans
64
Que 5
What is the periodic law for mendeleev periodic table
Ans
"The properties of elements are the periodic function of their atomic masses "is the periodic law for the mendeleev periodic table
Que 6
What is the name given to the vertical columns and horizontal rows in the periodic table
Ans
The vertical columns are called groups
Horizontal rows are called periods
Que 7
What are the limitations of mendeleev periodic table classification
Ans
The position of the hydrogen cannot be fixed as hydrogen has both the properties of alkali and the halogens
There is no place for the isotopes of the element
Que 8
What is the basis of Mendeleev periodic table
Ans
Mendeleev arrange the elements in order of their increasing atomic masses
Que 9
Who discovered atomic number
Ans
In 1913 Henry Moseley
Que 10
What is the basis of modern periodic table
Ans
The modern periodic table is arranged on the basis of the atomic number
Que 11
What is modern periodic law
Ans
Properties of elements are a periodic function of their atomic number
Que 12
How many vertical columns and horizontal rows are found in modern periodic table
Ans
There are 18 vertical columns known as groups
There are 7 horizontal rows known as periods
In order to understand different trends in the periodic table like valency atomic radius electronegativity metallic character non metallic character watch the attached lecture
How to find the position of an element in a periodic table just by its atomic number
What is the mass of hydrogen peroxide in one litre of 3M solution?
a) 10.2 g
b) 102 g
c) 11.3 g
d) 68 g
Ans (b)
Que 3
Decomposition of hydrogen peroxide is prevented by
a) NaOH
b) MnO2
c) glycerol
d) oxalic acid
Ans (c)
Que 4
Which of the following is used as a moderator in nuclear reactors?
a) Heavy Hydrogen
b) Ozone
c) Heavy Water
d) Hydrogen Peroxide
Ans (c)
Que 5
The oxidation number of oxygen in hydrogen peroxide is
a) 1
b) 2
c) -1
d) -2
Ans (c)
Que 6
The strength of 20 volume of hydrogen peroxide is
a) 13.6g/litre
b) 60.7 g/litre
c) 160 g /litre
d) 20.2 g/litre
Ans (b)
Que 7
25 volumes of hydrogen peroxide means
a) 25%H2O2
b) 25 cm^3 of the solution contains 1 gram of hydrogen peroxide
c) 1 cm^3 of solution liberates 25 cm^3 of O2 at NTP
d) 25 cm^3 of the solution contains 1 mol of hydrogen peroxide
Ans ( c)
Que 8
Ortho and para hydrogen differ in
a) Atomic Number
b) Mass Number
c) Electron Spin in two atoms
d) Spins of neutrons
Ans (d)
Que 9
The structure of hydrogen peroxide is
a) Planar
b) Non Planar
c) Spherical
d) linear
Ans (b)
Que 10
The O-O-H bond angle in hydrogen peroxide is
a) 106°
b) 109°28'
c) 120°
d) 101.9°
Ans (d)
Que 11
Commercial 11.2 volume H2O2 solution has a molarity of
a) 1
b) 0.5
c) 11.2
d) 1.12
Ans (a)
Que 12
Water gas is a mixture of
a) carbon dioxide and water
b) carbon monoxide and hydrogen
c) carbon monoxide and water
d) carbon monoxide and nitrogen
Ans (b)
Que 13
Hydrogen can be prepared by the action of dilute sulphuric acid on
a) Copper
b) Iron
c) Lead
d) Mercury
Ans (b)
Que 14
The degree of hardness of water is expressed in terms of
a) ppm by weight of magnesium sulphate
b) g/L of calcium carbonate and magnesium carbonate present
c) ppm by weight of calcium carbonate irrespective of whether it is actually present
d) ppm of calcium carbonate actually present in water
Ans (c)
Que 15
Permanent hardness of water is due to the presence of
(a)bicarbonates of sodium and potassium
(b) chloride and sulphate of sodium and potassium
(c) chloride and sulphates of calcium and magnesium
(d) bicarbonate of calcium and magnesium
Ans (c)
Que 16
The inorganic compound obtained by auto oxidation of 2 alkyl anthraquinol is
a) H2O
b) H2O2
c) H2
d) O2
Ans (b)
Que 17
A commercial sample of hydrogen peroxide is labelled as 10 volume its percentage strength is nearly
a)3%
b) 1%
c) 9%
d) 10%
Ans (a)
Que 18
Ortho and para hydrogen have
a ) identical chemical properties but different physical properties
b) identical physical and chemical properties
c) identical physical properties but different chemical properties
d) different physical and chemical properties
Ans ( a)
Que 19
Amongst H2O,H2S,H2Se,H2Te which one has highest boiling point
a) H2O because of hydrogen bonding
b) H2Te because of higher molecular weight
c) H2S because of hydrogen bonding
d) H2Se because of lower molecular weight
Ans (a)
Que 20
When Zeolite which is hydrated sodium Aluminium silicate is treated with hard water the sodium ions are exchanged with
a) H+ ions
b) Ca 2+ ions
c) (SO4) 2- ions
d) OH- ions
Ans (b)
Que 21
Hydrogen resembles halogens in many respect for which the several factors are responsible of the following factors which one is most important in this respect
a) tendency to lose an electron to form a cation
b) tendency to gain a single electron in its valence shell to attain stable electronic configuration
c) low negative electron gain enthalpy value
d) it's a small size
Ans ( b)
Que 22
Arrange LiH,NaH,KH,RbH,CsH them in order of increasing ionic characters
a) LiH>NaH>CsH>KH>RbH
b) LiH<NaH<KH<RbH<CsH
c) RbH<NaH>KH<CsH>LiH
d) RbH >CsH>KH>NaH>LiH
Ans (b)
Que 23
Which of the following hydride is electron precise hydride
a) B2H6
b) NH3
c) H2O
d) CH4
Ans (d)
Que 24
The oxide that gives H2O2 on treatment with dilute H2SO4 is
The compounds obtained from animal or plant Kingdom are called organic compounds
Vital force Theory
Berzelius proposed that synthesis of organic compounds within the plants and animals requires a mysterious force the source was called vital force and theory was referred as vital force theory
In 1828 Friedrich Wohler ,obtained urea an organic compound found in urine of mammals in laboratory
In this way first organic compound prepared in the laboratory
Organic chemistry is a chemistry of compounds of the carbon
Tetravalency of Carbon
Atomic number of carbon is 6 .Its electronic configuration is 2,4 so in order to attain noble gas configuration carbon atom either gain or loose four electrons but it involves of the large amount of energy required for this so by sharing electrons with other atoms forming covalent bonds
Tendency of carbon atom to form covalent bonds is known as tetravalency of carbon
Catenation
Carbon atom has a unique capacity to form bonds with other carbon atoms this property of forming bonds with the atoms of the same element is called catenation
Hybridisation
1) sp³ hybridisation---
The carbon atoms in alkanes have sp³ hybridization
In sp³ hybridization s orbitals are attached with three p orbitals with the Sigma bonds
These molecules are generally of tetrahedral shape eg methane
2) sp² hybridisation--
The carbon atoms in alkenes have sp² hybridization ie organic compounds which have double bond contain sp² hybridization
They consists of 1 Sigma and 1 pi bond
These are planar molecules
3) sp hybridisation --
The carbon compounds containing triple bond sp hybridised ie alkynes contain sp hybridisation
Sigma and Pi Bond
Sigma Bond --
Sigma bond is formed by end to end overlapping of bonding orbitals along the internuclear axis This overlapping is known as head on overlap or axial overlap
Sigma bonds are stronger than Pi bonds
Pi Bond --
Pi bond is formed by sideways overlapping of the half filled atomic orbitals of bonding atoms this overlap is known as sidewise over lap for lateral overlap
Pi bonds are found in unsaturated compounds
Classification of organic compounds
Organic compounds are broadly divided into
1) open chain--
These compounds contain open chains of carbon atoms in their molecules the carbon change may be either is straight chain or branched chain they are called aliphatic compounds
2) Closed chain --
These compounds contain closed chain of atoms in their molecules they are of three types
-- Alicyclic
This compound contains a ring of 3 or more carbon atoms in them
-- Aromatic Compounds
These compounds have a cyclic system containing at least one benzene ring the parent member of family is called benzene is a cyclic hexagon luring of 6 carbon atoms with three double bonds in the alternate positions
-- Heterocyclic Compounds
These compounds having contain one or more atoms of either nitrogen Oxygen or sulphur in addition to carbon atoms
Functional Groups
Functional group is a group of atoms within a molecule that has a characteristic chemical behaviour of an organic compound
Watch the lecture
What is homologous series
Homologous series is a series of similar constituted compounds in which the members was the same functional group and have similar chemical characteristics
Characteristics of Homologous series
1) All members can be represented by general formula
2) Two successive members differ in their formula by ---CH 2 group
3) All members in particular family have identical chemical properties and a proper gradation in the physical properties
4) All numbers present in particular series can be prepared by using similar methods
IUPAC Nomenclature of Organic Compounds---
In IUPAC system the name of an organic compound consist of three parts
1) Word root--
Word root denotes number of carbon atoms present in the chain eg C=1 is for meth C=2 for eth etc
2) Suffix--
Word Root is linked to suffix which may be primary or secondary or both
Primary suffix -- it indicates the nature of linkages in the carbon atoms
ane --for single bond
ene -- for double bond
yne -- for triple bond
Secondry Suffix --- it indicates the presence of functional group in the organic compound eg alcohol -- ol
3) Prefix -- there are many groups which are not regarded as functional groups these are regarded as substituents or side chains these are represented as prefixes and are placed before the word root by naming a particular compound
Watch the attached lecture to understand how to write IUPAC name of any compound
Classification of carbon atoms in alkanes
Carbon atoms in an alkane is classified as primary (1°) secondary (2°) tertiary (3°) and quaternary (4°)
Watch the lecture to understand the concept
Isomerism
Two or more compounds having same molecular formula but different physical and chemical properties are called isomers
The phenomenon of existence of two or more compounds using the same molecular formula but different properties is called isomerism
Types of Isomerism
Type 1
Structural Isomerism-- The compound having same molecular formula but different structures within the molecules are called structural isomers and this phenomenon is called the structural isomerism
a) Chain Isomerism -- a compound having same molecular formula but different arrangements of carbon chain within the molecule are chain isomers and this phenomenon is called chain isomerism due to this isomerism we have straight chain and branched chain of carbon compounds
-C--C---C----C. ----C---C----C
|
C
b) Position Isomerism-- The compounds have same molecular formula but differ in position of functional group, carbon carbon multiple bonds or substituent group are called position isomers and this phenomenon is called position isomerism
---C----C------C----OH. -----C-----C-----C
|
OH
c) Functional Group Isomerism-- The compounds having same molecular formula but different functional groups in the molecule this phenomenon is termed as functional group isomerism
----C----C----C=O. -----C----C----C
|. ||
H. O
Propanal Propanone
d) Metamerism --- The compounds having same molecular formula but different number of carbon atoms on either side of the function code are called metamers and this phenomenon is called metamerism
--C--C---CO---C---C C---CO---C---C---C
e) Tautomerism --
This isomerism is so much different their arrangement of atoms but they exist in dynamic equilibrium with each other
Stereo Isomerism--- The isomers which have same structural formula but have different relative arrangement of atoms or group of atoms in space are called stereoisomers the phenomena is called stereoisomerism
The compounds containing double bond show cis and trans isomerism is generally known as geometrical isomerism
The compounds which have same structural formula birthday per in the special arrangement of atoms about the double bond shows the geometrical isomerism
The isomer in which similar atoms or groups lie on the same side of the double bond is called exercise while the other in which they are displaced on the opposite side is called trans isomer
Watch the lecture
Hydrocarbons
Compounds which contain only carbon and hydrogen are called hydrocarbon hydrocarbons can be classified into three main categories
Saturated hydrocarbon -- The hydrocarbon which contain only single bonds are called saturated hydrocarbons they are also known as alkanes for example methane propane butane
Unsaturated hydrocarbon-- Hydrocarbons which contain double bond and triple bond are called unsaturated hydrocarbons when they contain double bond they are known as alkene when they contain triple bond they are known as alkyne
Aromatic hydrocarbon
The hydrocarbons which contain at least 1 special type of hexagonal ring of 6 carbon atoms with three double bonds in the alternate position is called aromatic ring or benzene ring
How to prepare alkanes in laboratory
Alkanes can be prepared by using any of the method
1) From unsaturated hydrocarbons
Saturated hydrocarbons are converted into alkanes by catalytic hydrogenation
In this process hydrogen gas is passed in the presence of nickel platinum or palladium and as a result unsaturated hydrocarbon is converted into alkane
Pd/Pt/Ni
Alkene- +H 2 -------------- - Alkane
Alkanes can be prepared in laboratory by heating sodium acetate with the 16 line in a copper to the methane Gas produced is collected over Water because it is insoluble in water the whole process explained in the lecture given below
Wurtz Reaction
When alkyl halide usually bromide or iodide is treated with sodium in dry ether asymmetrical alkane containing twice the number of carbon atoms of alkyl halide is obtained this method gives alkene with even number of carbon atoms
RX+2Na+XR- -------------------R--R. + 2NaX
dry ether
Alkene
Hydrocarbons with double bond are known as alkene eg ethene ,propene
They can be prepared by halo alkanes
When haloalkanes are treated by alkali (Na OH) in presence of alcohol halo alkanes are converted into alkane
Sandmeyer Reaction
Benzene diazonium chloride is converted to chlorobenzene on treatment with copper chloride is known as sandmeyer reaction
Cannizaro Reaction
Aldehydes having no Alpha hydrogen forms alcohol and acid on treatment with concentrated alkali(NaOH)
How to form iodoform compounds
Haloalkanes are treated with sodium iodide and acetone to form idoalkane
Huckel Rule
Huckel Rule is very useful in finding weather organic compound is aromatic or not
How to recognise whether it is aromatic compound or not watch the lecture
Hydrogen has one electron so it has equal tendency to lose or gain one electron when it loses one electron it resembles alkali metals when it came one electron it resembles halogens
Isotopes of hydrogen
Hydrogen contains three isotopes protium(H) deuterium(D) and tritium(T)
Preparation
Hydrogen can be prepared by electrolysis of dilute sulphuric acid or dilute sodium hydroxide using platinum electrodes
Industrial preparation
Hydrogen is prepared from water gas known as Bosch process
C+H2O- ------- C O+H2
Properties of hydrogen
Hydrogen is colourless odourless tasteless it is highly combustible and diatomic gas at room temperature
Chemical Reactions
Hard water and Soft water
Soft water
The water which gives lather with the soap is known as soft water soft water is fit for drinking
Hard water
The water which does not give lather with the soap is known as hard water hard water is not fit for drinking the hardness of water is of two types of temporary hardness and permanent hardness
Temporary hardness in the water is due to presence of bicarbonates of calcium and magnesium hardness can be removed by boiling or treated it with lime
Permanent hardness in the water is due to presence of chloride and sulphate
Permanent hardness can be removed by using some special techniques for example Permutit process ion exchange process calgon process
Na 2 CO 3 sodium carbonate removes both temporary and permanent hardness of water
Ortho and Para Hydrogen
Ortho hydrogen
Molecules of hydrogen in which the spins of both the nuclei are in the same directions that is parallel nuclear spins
Para hydrogen
Molecules of hydrogen in which the spins of both the nuclei are in opposite direction that is they have anti parallel nuclear spin
Heavy Water
D 2 O is the symbol of heavy water electrolysis of heavy water results in deuterium
Hydrogen peroxide
H 2 O 2
Hydrogen peroxide is an unstable liquid at room temperature and 1 imposes into water
2H2O2-------2H2O+O2
Some Important Terms
Lattice Enthalpy --
Lattice enthalpy is amount of energy required to break one mole of a solid salt into its ion
Greater the lattice enthalpy more will be the energy required to break the lattice
Hydration Enthalpy
It is the amount of energy released when one mole of a solid salt gets dissolved in water
Note -- for Solubility of salt kinetic energy change should be negative
Hydration enthalpy is more more than lattice enthalpy salt will dissolve
Hydration enthalpy is less than lattice enthalpy salt will not dissolve
Alkali Metals
Li,Na,K,Rb,Cs,Fr
General electronic configuration of s block elements is ns¹
The existence monovalent ions
they are highly electropositive
very strong reducing agent
Their compounds are highly soluble in water and form colourless solution
Important question answers on s block elements
Que
Explain why sodium is less reactive than potassium?
Ans --Ionization enthalpy of potassium is less than of sodium or potassium is more reactive than sodium
Que --
Why are potassium and caesium rather than lithium used in photoelectric cells?
Ans -- Potassium and caesium have much lower ionization enthalpy therefore these metals on exposure to light easily limit electrons but lithium does not
Que. --
Which of the alkali metals sodium potassium rubidium and caesium have least melting point?
Ans -- Increase in size the strength of metallic bonding decreases there for melting point also decreases so caesium has the least melting point
Que --
Which alkali lithium sodium potassium caesium give the hydrated salt
Ans-- Lithium is the smallest and highest charge density so it is maximum hydrated
Que --
When burnt in air lithium forms normal oxide sodium the peroxide and the potassium superoxide why
Ans --
Lithium of very small size and has a strong field around it so it cannot stabilize other large anions so it forms only normal oxide where are sorry I'm being large in size and can stabilize large can oxide so it forms peroxides where as potassium being large can also stabilizer large superoxide ion forming superoxides
Que -- LiH is more stable than NaH why ?
Ans --
Both lithium and hydrogen have a small size and their combination has high lattice energy so lithium hydride is more stable
Que -- Sodium metal is kept under kerosene why?
Ans -- Sodium metal is very reactive when exposed to air it reacts with oxygen moisture and carbon dioxide present in the air to prevent these reactions and protect the metal sodium is kept under kerosene
Que -- Why is LiF almost insoluble in water whereas LiCl is soluble not only in water but is also in acetone?
Ans -- Lithium and fluoride have a small size therefore lithium fluoride has high lattice enthalpy all the hydration enthalpy of lithium fluoride is also high but it is less than lattice enthalpy
Lithium chloride has lower lattice enthalpy than corresponding hydration enthalpy so therefore it is soluble in water has also some covalent character because of greater polarization so it is also soluble in nonpolar solvents like acetone
Alkali metal compounds are
Sodium oxide(Na 2 O)
Sodium peroxide(Na 2 O 2)
Sodium hydroxide (Na OH)
Sodium Carbonate(Na 2 CO 3)
Its common name is washing soda
Sodium bicarbonate (Na HC O 3)
Its common name is baking soda
Sodium Sulphate Na 2 SO 4
Its common name is salt cake
Glauber ' s Salt[Na2SO4.10H2O]
Microcosmic Salt [Na(NH 4) HPO 4]
Group 2 Alkaline Earth Metals
Be,Mg,Ca,Sr,Ba,Ra
Group 2 of periodic table is also known as alkaline earth metals
Outermost layer of two valence electrons
Compounds of group 2 metals
Electronic configuration--
Electronic configuration of alkaline earth metals is ns²
Ionization enthalpy--
Alkaline earth metal have low ionization enthalpy but first ionisation enthalpy of alkaline earth metals are higher than those of alkali metals but second ionization enthalpy values of alkaline earth metals are smaller than those of alkali metals
Reactivity towards oxygen
Beryllium and magnesium are kinetically inert towards oxygen because of the formation of a film of oxide on their surface but the reactivity with oxygen increases as we move down the group to to increasing electropositive character of the elements
Some Important compounds of Alkaline Earth Metals
Magnesium oxide MgO
Magnesium chloride Mg Cl 2
Epsom salt MgSO4.7H2O
Magnesium carbonate Mg CO 3
Calcium oxide(Quick Lime - Ca O)
Calcium hydroxide (slaked lime - Ca OH 2)
Calcium Carbonate(limestone- Ca CO 3)
Calcium Sulphate & Gypsum(CaSO4.2H2O)
Mock test series
S block Elements
1) The concentration of chlorine lead nitrate and iron in a water sample from an underground lake was found to be 1000ppb,40ppb,100ppb,0.2ppm. water is unsuitable for drinking due to high concentration of
a) lead
b) nitrate
c) iron
d) fluoride
Ans (b)
2) Which of the following atom has highest first ionization energy?
a) Na
b) K
c) Sc
d) Rb
Ans (c)
3) Hydrogen peroxide in its reaction with KIO 4 and NH 2 OH is acting as
a) reducing agent , oxidising agent
b) reducing agent, reducing agent
c) oxidising agent, oxidising agent
d) oxidising agent, reducing agent
Ans (a)
4) Dilute aqueous solution of sodium sulphate (Na 2 SO 4) is electrolysed using platinum electrodes the products at the anode and cathode are
a) O2,H2
b)S2 O 8 ^-2,Na
c) O2,Na
d)H2,O2
Ans (a)
5) The oxide that gives hydrogen peroxide on treatment with dilute acid is
a) Pb O 2
b) Na 2O 2
c) Mn O 2
d) TiO2
Ans (b)
6) The temporary hardness of water is due to calcium bicarbonate can be removed by adding
a) Ca CO 3
b) Ca(OH)2
c) Ca Cl 2
d) HCl
Ans (b)
7) Which of the following alkaline earth metal sulphates has its hydration enthalpy greater than its lattice enthalpy?
a) Ca SO 4
b) Be SO 4
c) Ba SO 4
d) Sr SO 4
Ans (b)
8) The material used in solar cells contain
a) Cs
b) Si
c) Sn
d) Ti
Ans (b)
9) The oxidation state of most electronegative element in the products of the reaction Ba O 2,with dil H 2 S O 4 are
a) 0 and -1
b) -1and -2
c) -2 and 0
d) -2 and -1
Ans (d)
10) Molecular formula of Glober' s salt
a) MgSO4.7H2O
b) CuSO4.5H2O
c) FeSO4.7H2O
d) Na2SO4.10H2O
Ans ( d)
P block elements
General electronic configuration group 13 elements is ns²np1
Que --
What is the oxidation state of boron in boric acid what is the basic city of boric acid
Ans -- Formula of Boric Acid - H3 BO 3 . Oxidation state of boron in boric acid is +3 gas it is mono basic acid
Que --
Anhydrous Al Cl 3 is covalent but it becomes ionic in aqueous solution
Ans - Energy released during hydration is greater than ionization enthalpy for ammonium so it is ionic in solution
Que --
Explain why Aluminium though electropositive metal finds extensive use of structural materials
Ans -- Aluminium reacts with air to form a hard protective layer of aluminium trichloride which protects it further action so it becomes passive so it is extensively used as a structural material
Que -- why BCl 3 has zero dipole moment?
Ans --
It has symmetrical trigonal structure in which all three BCl bonds are oriented at an angle of 120 degree to one another so they cancel dipole moment of each other giving the dipole moment of zero
Que - Why does gallium undergo disproportionation reaction?
Ans -- Gallium shows both +1 and + 3 oxidation States due to inert pair effect however its + 3 oxidation state is more stable and hence undergoes disproportionation reaction
3Ga+ ------------- 2Ga + Ga 3+
Que -- what are silicones
Ans -- silicon sar synthetic organic silicon
R
|
compounds --Si--O --. units held by Si-O--Si
|
R
They are hydrophobic that is water repellent in nature
Que --
Why boron trifluoride behave as a Lewis acid
Ans -- BF 3 only 6 electrons around B and its valence shell therefore needs two more electrons to complete its octet so it readily accept a pair of electrons from Lewis bases and behaves as a Lewis acid
Group 18
Nobel Gases
Electronic configuration of noble gases is ns²np⁶
In their valence shell 8 electrons are present so there octet is complete
So they are inactive and also known as inert gases
Properties of noble gases are compromised in the lecture attached given below
The ionic size of Na+,Mg2+,Al3+,Si4+ follows the order
a) Na+<. Mg2+.< Al3+<. ,Si4+
b)Na+. > Mg2+. >Al3+. >,Si4+
c) Na+. >Mg2+. <Al3+>. ,Si4+
d) Na+.< Mg2+. >Al3+. <,Si4+
Ans (b)
Que 3
The correct order of ionic radii in the following isoelectronic species
a) S2->Cl->K+>Ca2+
b)S2-<Cl-<K+<Ca2+
c)S2-<Cl->K+>Ca2+
d)S2->Cl->K+<Ca2+
Ans (a)
Hint
Greater the charge less the radius
Que 4
The correct order of increasing radii of the elements. Na ,Si,Al,P is
a) Si,Al,P,Na
b) P,Si,Al,Na
c) Si,P,Na,Al
d) P,Al,Si,Na
Ans (b)
Hint
Sodium has more ionic radius
Que 5
The correct order of increasing radii of the following elements ( Na ,Rb,K,and Mg)
a) Mg,Na,K,Rb
b) Mg,K,Na,Rb
c) Na,K,Rb,Mg
d) Na,Rb,K,Mg
Ans (a)
Rb has greater radius
Hint
Radius decreases in period and increases in group
Que 6
The penetration of the electrons in any principal shell varies as
a) s. >p. > d. >f
b) s. <p. <d. <f
c) s. >p. < d. <f
d) s.< p. >d. <f
Ans (a)
Que 7
Which of the following configuration is expected to have maximum difference in second and third ionization enthalpies
a) (1s)^2, (2s)^2 ,(2p)^2
b) (1s)^2, (2s)^2 ,(2p)^6 (3s)^1
c) (1s)^2, (2s)^2 ,(2p)^1
d) (1s)^2, (2s)^2 ,(2p)^6 (3s)^2
Ans ( a)
Que 8
In which of the following compound the ratio of anion size to the cation size have the lowest value
a) NaCl
b) KCl
c) NaBr
d) MgCl2
Ans (b)
Que 9
Which of the following process proceed with the absorption of energy ie endothermic reaction
a) F------(F)-1
b) (O-)-----(O)2-
c) Cl----(Cl)-1
d) H----(H)-1
Ans (b)
Hint
(O-) will tend to resist the addition of another electron
Que 10
Which pair of atomic number represents s block elements
a) 7,15
b) 6,12
c) 9,17
d) 3,12
Ans (d)
Que 11
Which of the following configuration of an atom has the lowest ionization enthalpy
a) (1s)^2,(2s)^2,(2p)^6
b) (1s)^2,(2s)^2,(2p)^5
c) (1s)^2,(2s)^2,(2p)^3
d)(1s)^2,(2s)^2,(2p)^5,(3s)^1
Ans ( d)
Que 12
The correct order of electron gain enthalpy with fluorine chlorine bromine is
a) F. <Cl. <Br. < I
b) Cl >F >Br. > I
c) F. > Cl. <Br. < I
d) F. > Cl. >Br. <I
Ans (b)
Que 13
Which of the following group represent the collection of isoelectronic species
(At no of Cs=55,Br=35)
a) (N)3-,(F)-,(Na)+
b) (Be),(Al)3+
c) (Ca)2+,(Cs)+,Br
d) Na+,(Ca)2+, (Mg)2+
Ans. ( a)
Hint
Atoms having same number of electrons
Que 14
The group of elements in which differentiating electron enters the antipenultimate shell of atoms
a) f block elements
b) d block elements
c) p block elements
d) s block elements
Ans (a)
Que 15
The polarizing power of the following anions follow the order
a) (N)3->F->O2-
b) (O)2->N3->F-
c) O2->F->N3-
d) N3->O2-.>F-
Ans (d)
Recorded lectures attached below are very helpful in order to solve the different multiple questions given above in the post
Topic covered in this lecture
How to find the group and period using atomic number that is using the electronic configuration using Afbau principle
There are different properties of the elements like their ionic radius and ization enthalpy electronegativity melting point boiling point and how they varies and the periodic table that is there trends by watching the given lecture you can get the tricks to solve the different types of questions
Conductivity (unit siemens) is directly proportional to area of the vessel and the concentration of solution in it and is inversely proportional to the length of the vessel then the unit of constant of proportionality is
a) Sm/mol
b) Sm^2/mol
c) S^-2m ^2 mol
d) S^2m^2/mol^2
Ans (b)
Que 2
Out of molar conductance versus √C in a strong electrolyte is
a) circular
b) linear
c) parabolic
d) sinusoidal
Ans (b)
Que 3
The quantity of electricity required to liberate 0.1 gram equivalent of an element at the electrode is
a) 9650C
b) 96500 C
c) 965C
d) 96.5C
Ans (a)
Que 4
On passing 3 A of electricity for 50 minutes 0.1 g of metal deposits Equivalent mass of the metal is
a) 20.5
b) 25.8
c) 19.3
d) 30.7
Ans (c)
Que 5
EMF of the cell is
a) sum of two oxidation potential
b) sum of two potentials
c) difference of two electrode potentials
d) none of above
Ans (c)
Que 6
Cell constituted by two electrodes A/A+=-0.35 V and B= B/B+ = 0.42 V calculate the EMF of the cell
a) 0.07V
b) 0.77V
c) -0.77V
d) -0.07 V
Ans (b)
Que 7
Out of copper silver iron and zinc the metal which can displace all others from their salt solution is
a) silver
b) copper
c) zinc
d) iron
Ans ( c )
Que 8
The EMF of a cell is positive when free energy change of reaction is
a) greater than 0
b) less than 0
c) equal to 0
d) relationship of free energy change and emf
Que 9
Hydrogen electrode is placed in the solution whose pH is 10 or potential of this electrode will be
a) +0.591 V
b) - 0.591 V
c) 0
d) none of these
Ans (b)
Que 10
When a lead storage battery is charged it acts as a
a) primary cell
b) galvanic cell
c) concentration cell
d) electrolytic cell
Ans (d)
Electrochemical cell or galvanic cell
The device in which chemical energy released during a chemical reaction is converted to electric energy
Electrochemical series
The arrangement of metals in decreasing order of tendency to lose electrons
Watch lecture to understand what is electrochemical series on how the position of elements in the electrochemical seriesis helpful in determining various types of properties
Nern'st equation of cell
Relationship between electrode potential and concentration of solution is all known as nernst equation
Batteries
Battery is arrangement of one or more cells connected in a series and used where the chemical energy of the redox reaction is converted into electrical energy
Two types of batteries
1) Primary Battery
Batteries in which cell reaction occurs only once and the battery becomes that after the use over a period of time and cannot be reused again
Eg mercury cell, Leclanche cell
2) Secondry Batteries
These batteries are rechargeable ,on charging the reaction becomes reverse
Eg lead storage battery
Fuel cell
This was used as a primary source of electric energy on the moon flights these are the means by which chemical energy may be converted into electrical energy
Solutions Class 11 Concepts along with numericals are explained in form of video lecture
How to find Molarity
Formula
Molarity =
Number of moles(solute)/volume of solution ( litre)
In the video lecture attached given below explain how to find the molarity in both Hindi and English especially the numericals based on molarity are explained The questions are discussed in this video are
Que 1
40 gram of NaOH is dissolved in 500 ml of water find the molarity
Que 2--
1/10 mole of solute is dissolved in hundred gram of solvent calculate molality
Que 3
Calculate molality of 20% by weight of NaOH solution
Que 4
15 gm of KCl is dissolved in 1L of water find molarity
Solution---
How to find Normality
Formula of Normality
= Equivalent weight of solute / volume of solvent (litre)
Question discussed in given lecture are
Que 1
Find normality of 6 gram of sulphuric acid dissolved in 250 cm³of water
Que 2
4 gram of NaOH are dissolved in 200 cm³ of water find molarity
Solution---
Mole fraction and Henry Law
The lecture attached below contain explanation how to find out solutions of questions on mole fraction and the Henry's law
Mole fraction---
It is ratio of mole fraction of solute to sum of mole fraction of solute and solvent
Henry Law
Solubility of a gas in a liquid at a particular temperature is directly proportional to pressure of gas in equilibrium with liquid
P~Kh×x
Que 1
Calculate mass percentage of benzene and carbon tetrachloride if 22 gram of benzene is dissolved in 122 gram of carbon tetra chloride
Que 2
Calculate mole fraction of water in mixture of 13 gram of water ,108 gram of acetic acid and 92 gram of ethyl alcohol
Que 3
Calculate solubility of methane in benzene at 298K under 760 mm of Hg where Henry constant is 4.27 ×10⁵ mm of Hg
Multiple choice questions
Questions discussed in attached video are
1) Find isotonic solutions where A = 0.1 M of Glucose ,B = 0.05 M of NaCl ,C= 0.05 M of BaCl2 ,D= 0.01 M of AlCl3
2) If A= 0.5 M of C2H5OH ,B= 0.1 Mg3(Po4) C= 0.250 M of KBr , D= 0.3 M of Na3Po4 .which one has highest vantHoff Factor
3) If toothpaste of 500 gram contain 0.2 g of fluoride find concentration of fluoride in PPM
Watch the lecture to solve questions of thermodynamics
Chemical thermodynamics
The study of energy transformations from one form to another is a studied under thermodynamics
System
three types of system
Open system
The system which can exchange energy as well as matter with the surroundings for example tea in a cup
Closed System
Message kam English there is exchange of only energy with the surroundings but not the matter for example hot water in a sealed tube
Isolated System
Septum which is perfectly insulated and which cannot exchange energy and matter with the surroundings for example ice in a thermos flask
Thermodynamic properties
Intensive property
The property which does not depend upon the quantity of matter present in the system for example temperature density
Extensive property
The property which depends upon the quantity of matter present in the system for example mass volume
There are following type of processes are found in the thermodynamics
Adiabatic process
The process in which system does not exchange heat with its surroundings
dQ=0
Isothermal process
The process in which temperature remains constant
dT=0
Isobaric process
The process in which change of state is brought about at constant pressure
dP =0
Isochoric process
The process in which volume of the system remains constant
dV=0
Cyclic process
This is the process in which a system undergoes a number of different states and finally returns to its initial state for the whole process change in internal energy and change in enthalpy is zero
Heat
The quantity of energy which flows between the system and surroundings on account of temperature difference is called heat it is a path function that is depends upon the path followed
H= ms ∆t
m is the mass of substance
s is specific heat
∆t is temperature difference
Heat Capacity
The amount of the heat required to raise the temperature of the system by 1 degree Celsius
C=q/ ∆T
if the system consists of a single substance and weight 1 gram the heat capacity of the system is known as specific heat of the system
Q=mC∆t
Internal energy
The total amount of energy associated with a molecule is known as internal energy it is denoted by U
At T = constant ∆U =0
Enthalpy
The total heat content of a system at constant pressure is called enthalpy of the system it is the sum of internal energy and product of pressure volume work it is extensive property and represented symbol by H
H= E+pV
∆H=∆E+p∆V
∆H=∆E+∆nRT
Laws of thermodynamics
First law of thermodynamics
Energy can neither be created nor destroyed it can be changed from one form to another
∆E=q+W
∆E = q+p∆V
∆E is change in internal energy
q is heat absorbed
W is work done
Second law of thermodynamics
For a spontaneous process of an isolated system the entropy change is always positive
∆S = q/T = ∆H/T
Third law of thermodynamics
The entropy of a substance becomes zero at absolute zero temperature
S=0
Importance of third law is that it is used in calculating absolute entropy is of pure substances at different temperatures
∆S= CpdT/T
Hess's Law of constant Heat
Total enthalpy change during the complete course of reaction in a single step and several steps are equal
∆H=∆H1+∆H2+∆H3
Gibbs free energy
Images of the reactions change in enthalpy and entropy occurs simultaneously so a new function is introduced to define the spontaneity of a chemical process known as Gibbs free energy which gives a relationship between enthalpy and entropy
Known as Gibbs Helmholtz equation
∆G = ∆H-T∆S
The process is spontaneous as gibbs free energy is negative
it is an equilibrium if Gibbs free energy is equal to 0
and it is non spontaneous if gibbs free energy is positive
Isostructural species are those which have same shape and hybridization among the following identify the isostructural pairs
a) NF3 and BF3
b) BF4- and NH4+
c) BCl3 and BrCl3
d) NH3 and NO3-
Ans ( b)
Hint
BF4- and NH4 + are tetrahedral
Que 2
Hydrogen bonds are formed in many compounds the boiling point of such compounds depends to a large extent on the strength of hydrogen bond and the number of hydrogen bonds the correct order of decreasing order of boiling points
a) HF>H2O>NH3
b) H2O >HF>NH3
c) NH3>HF>H2O
d) NH3>H2O>HF
Ans (b)
Que 3
In ( PO4)3- ion the formal charge on the oxygen atom is
a) +1
b) -1
c) -0.75
d) +0.75
Ans (c)
Hint
Formal charge = Total charge/no of O atom
= -3/4
=-0.75
Que 4
In ( NO3)- number of bond pairs and lone pairs of electrons on nitrogen atom are
a) 2,2
b) 3,1
c) 1,3
d) 4,0
Ans (d)
Que 6
In which of the following substances will hydrogen bond is strongest
a) HCl
b) H2O
c) HI
d) H2S
Ans (b)
Que 7
The electronic configuration of the outermost shell of the most electronegative element is
a) 2s^2,2p^5
b) 3s^2,3P^5
c) 4s^2,4p^5
d) 5s^2,5p^5
Ans ( a )
Que 8
Which element has highest ionisation enthalpy
a) 3s^2, 3p^1
b) 3s^2,3p^3
c) 3s^2,3p^2
d) 3d^10,4s^2,4p^3
Ans ( b)
Que 9
Which option represent correct bond order
a) (O2)->(O2)>(O2)+
b) (O2)-<(O2)<(O2)+
c)(O2)->(O2)<(O2)+
d) (O2)-<(O2)>(O2)+
Ans (b)
Que 10
Paramagnetic Species are
a) O2-
b) B2
c) F2
d) N2
Ans (a)
Recorded Lectures
Lewis structure
Ionic bonding
Electron Gain Enthalpy
How to find which bonding is present
What is Bond Enthalpy
What is Bond Length
Trick to find dependence of bond angle bond length and dipole moment
Ncert solutions chemistry -Kinetic Theory of Gases
Multiple choice Questions
Que 1
At what temperature the RMS velocity of Sulphur dioxide be same as that of oxygen at 303 K
a) 273K
b) 606K
c) 303 K
d) 403K
Ans (b)
Que 2
The ratio of root mean square velocity to average velocity of a gas molecule at a particular temperature is
a) 1:1.086
b) 1086:1
c) 2:1.86
d)1.86:2
Ans ( b )
Que 3
Average velocity of an ideal gas molecule at303 K is 2m/s the average velocity at 1200 K will be
a) 6m/s
b) 4m/s
c) 2m/s
d) 8 m/s
Ans (b)
Que 4
What is the temperature at which the kinetic energy of 0.3 mole of helium is equal to kinetic energy of 0.4 mole of argon at 400 K
a) 400 K
b) 873 K
c) 533 K
d) 300 K
Ans ( c)
Que 5
Root mean square velocity of a gas is double when temperature is
a) increased 4 times
b) increased to 2 times
c) reduced to half
d) reduce to one fourth
Ans (a)
Que 6
Sample of gas has a volume of of 0.2 litres at 1 atm pressure and 0°C At the same pressure but at 273 °C its volume will become
Numericals on Gaseous law
Boyles Law
Boyles law gave a relationship between pressure and volume of a gas at a constant temperature
P~1/V
PV = constant
Question which I discussed in the given lecture is
Gas at 298 K shifted from a vessel of 250 cm² capacity to that of 1 litre capacity find change in pressure
Charles law
Charles law gives a relationship between volume and temperature of a gas at a constant pressure according to Charles law as we increase the temperature the volume of the gas increases and vice versa
V~T
Question which is explained in given lecture is
300 ml of gas at 27° C is cooled to 3° C at constant pressure find final volume of the gas
More Numericals on Kinetic Theory if gases
Que1
A gas occupies 15 L at a pressure of 40mm Hg what us volume when pressure increased to 75mm Hg
Que 2
A gas occupies 12 L at 0.860 atm what is pressure if volume becomes 18 L
Que 3
Given 300 ml of a gas at 25°C what is its volume at 14°C
Que 4
At 250°C a gas has volume of 7.50 L what is its volume of gas at -24° C
Que 5
If a gas is pressured from 20 atm to 32 atm and critical temperature is 45°C what would be the final temperature in degree celcius
Que 6
Temperature of a sample of gas in a steel container at 30kPa is increased from -10° C to 1×10³° C what is final pressure
Problems discussed in attached lecture are
Type 1
A gas at 298 K is shifted from a vessel of 250 cm² capacity to that of 1litre capacity .Find change in pressure
Type 2
300 ml of a gas at 27° C is cooled to 3°C at constant pressure Find final volume
Gay Lussac Law
Numericals on combined gas Law
A gas occupies 7.6 litres at 27 ° C and 800 mm Hg what is its volume at STP
Concept of average root mean square and most probable velocity
Formula and Theory
Average velocity
Vav= √8KT/πM. =√8RT/πM
Root Mean Square velocity = √3RT/M
Most Probable Velocity = √2RT/M
What is ratio between most probable average velocity and rootmean square velocity
in the spectrum when the electron falls from nth level to ground level
n(n-1)/2
Angular Momentum
mvr=nh/2π
Energy of an electron in an orbit
E=13.18Z^2/n^2 KJ /mol
E=21.8Z^2/n^2 J/atom
E= -13.6Z^2/n^2eV/atom
Radius of orbit
r=0.059n^2/Z
Photoelectric effect
Kinetic energy of ejected electron
KE (1/2mv^2) = hv-hvo
Work function =hvo
De broglie relation
Wavelength = h/mv
Uncertainty principle
∆x×∆p= h/4π
Orbital and value of l
0 ------- s
1--------p
2------- d
3--------f
Sequence of energy levels
1s,2s,3s,3p,4s,3d,4p,5s,4d,5p,6s,4f
Quantum Number
There are four types of quantum numbers
1) principal quantum number (n)
2) azimuthal quantum number(l)
3) magnetic quantum number(m)
4) spin quantum number(s)
If we have an element Sodium
Then as we know atomic number of sodium is 11
Its configuration is 2,8,1
Or according to Afbau
1s^2,2s^2,2p^6,3s^1
Now
For example for 2p^6
Principal quantum number is 2
Azimuthal quantum number is =1
As for s orbital it is equal to 0
For p orbital it is equal to 1
For d orbital it is equal to 2
For f orbital it is equal to 3
Magnetic quantum number varies from
(-l to +l)
So m= -1,0,+1
Spin quantum number
+1/2,-1/2
Spectrum of hydrogen atom
When any electron jumps from one shell to another either by absorbing or emission of energyenergy spectral lines are emitted from atom
There are different series
Lyman
Balmer
Paschen
Brackett
Pfund
Numericals on hydrogen spectrum
Wave length of spectral lines emitted can be calculated by using formula
1/lambda=R[1/n^2-1/n'^2]cm
There is a relationship between
wavenumber and wavelength
wave number~1/wave length
Que --
what is the frequency of the spectral line limited when the electron in n= 3 in hydrogen atom de exites to the ground state Rydberg constant is 109737cm^-¹
Important questions which are useful for questions asked in different competitive exams are discussed in attached lecture
Que -- If ¹H1,²H1, ⁴He2,⁸Li 3 all have one number of electrons is there is a transition of electron from n =2, n = 1 find the relationship between the wavelength emitted
Que --
If an atom is in nth excited state it comes to first excited state by emitting 10 different wavelengths find the value of the end
Que --
A hydrogen atom in its ground state is irradiated by light of wavelength 970 A° if HCF is equal to 1237×10^-⁶ find the energy of the incident light
Que --Find the ratio of maximum wavelength of lyman series to maximum wavelength of the Pashen series
