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Showing posts with label 10-Science. Show all posts
Showing posts with label 10-Science. Show all posts

## MCQ questions for class 10 --Science

### Sample Test Series  Term 2

Carbon and its Compounds

Que 1

A ray  is reflected by a plane mirror The angle of incidence for reflected ray is

a) 90°.

b) 0°.

c) 180°

d) 45°

Ans ( b)

Solution

by

Que 2

The focal length of a convex lens is 10 cm  one half of the lens is covered with black paper which one is correct

a) The image formed is one half of  original image

b) A complete images formed but of less intensity

c) The image  is formed above the principal axis

d) No image is formed

Ans (b)

Solution

Que 3

Which statement is correct

a) Medium B has more refractive index

b ) Medium A is more optically denser medium

c) Both are same but angle of incidence is critical angle

d) Medium A is optically denser so it is rarer medium

Ans ( b)

Solution

Que 4

Which colour has more speed in prism

a) P

b) Q

c) R

d)  S

Ans (a)

Solution

Que 5

Which colour of light has more wavelength in prism

a) P

b) Q

c) R

d) S

Ans  (a )

Solution

If speed of light in air is 3×10⁸ m/s and  speed of light in water is 2.2 ×10⁸ m/s then refractive index is

a) 1.4

b) 2.4

c) 1.5

d ) 1.22

Ans (a)

Solution

Que 9

If two thin lenses of focal length 20 cm and -25 cm are combined togethertogether to form a single lens .Then power of combination is

a) 5 D

b) 1D

c) -4 D

d) 9D

Ans ( b)

Solution

Part 10

If we use a concave mirror  of focal length 2.5 cm as a dentist mirror the distance of tooth from mirror

a) less than 2.5 cm from focal length

b) more than 2.5 cm from focal length

c ) less than 5 cm from focal length

d ) more than 5 cm from focal length

Ans ( a )

Solution

Part 11

At what distance the object should be placed in front of a concave mirror of focal length 20 cm to get an erect image

a) 10 cm

b) 20 cm

c) 25 cm

d) 40 cm

Ans ( a)

Solution

Part 12
In which year the concentration of hydrogen ion is highest

a) 2008

b) 2012

c) 2016

d) 2020

Ans (c)

Solution

Part 13

Find the order of reactivity of metals

a) Zn >Al >Cu

b) Al> Cu > Zn

c) Cu>Zn >Al

d)  Al> Zn >Cu

Ans (d)

Solution

Part 14

Electronic Configuration.                 Formula

I   A : 2,1.       B:2,6                                  A2B

II  B: 2,6.         C : 2,7.                               B2C

III.  C:2,7.         D: 2,8,3.                            DC3

IV.   E: 2,8,6.     F : 2,8,8,2.                        FE3

Which is wrongly formed

a ) I and II

b) II and III

c) III and IV

d ) I and  III

Solution

Part 15

Parent Acid.              Parent Base

a) HCl                        KOH

b ) H2CO3.                 KOH

c ) H3PO4.                 K2SO4

d) H2SO4.                  K2SO4

Which of the option represent parent acid and parent base of potassium carbonate

Solution

Part 15

The table shows reaction of few elements with NaCl and NaOH Which of the elements form amphoteric oxides

Element.          HCl.        NaOH

A.                       ×.              ×

B.                       ✓.               ✓

C                        ✓.                ×

D                         ✓.                ✓

a) A and D

b ) B and  D

c) A.  and.  C

d )  B and.  C

Solution

Part 16

Element.            Configuration

A.                     2,8,1

B.                     2,8,2

C.                     2,8,7

D.                     2,8,5

Identify the elements which combine ionic compounds

a)   A and B

b ) B and.  C

c ) A,B and D

d) A and C

Solution

Part 17

The equation given below depicts which type of chemical reaction

A+ BC -------- AC  + B

a ) Combination

b ) Decomposition

c ) Displacement

d ) Combustion

Solution

Part 18

Identify which substance is oxidised and which one is reduced

CuO + H2 --------------- Cu + H2O

Oxidised.            Reduced

a).  CuO.                   H2

b)  H2.                      CuO

c) H2O.                       Cu

d) Cu.                        H2O

Solution

Part 19

When a blue litmus paper is brought near the mouth of  delivery tube

a) It turns red

b) It turns. green

c) It remains blue

d ) It will dry

Solution

Part 20

A child runs towards a plane mirror with a velocity of 2m/ s With what speed will her image move towards her

a) 2m/s

b) zero

c) 4 m/ s

d) 6 m/ s

Solution

Part 21

A tank of water appears to be 1 m deep Calculate its actual depth if refractive index of water is 4/ 3

a) 4/3 m

b ) 3/ 4 m

c) 5/3 m

d ) 3/ 5 m

Solution

Part 22

For a given lens new focal length f'of lens is

a) f'<f

b ) f'=1/f

c) f'=f

d) f'= 2f

Solution

Part 23

The pH of four substances are

Substance.              pH

A.                             8.7

B.                              5.5

C.                              1.7

D.                             12.3

Identify the basic compounds from goven substance

a). A and B

b). B and C

c) A and   D

d)  C and D

Solution

Part 24

The electronic. configuration of
A ,B and C

A: 2,8.    B: 2,8 ,7.      C : 2,8,1

Which of the element is non metal

a) A

b) B

c) C

d) A and C

Solution

Part 25

An electrician want to use piece of element
to complete a broken circuit

Element.   Insulator. Melting point  Ductility

W.               ✓.                  Low.                  ×

X.                 ×.                   High.                  ✓

Y                   ✓.                 Low.                   ✓

Z.                  ×.                High.                     ×

Which element is used by electrician

a) W and Z

b ) X only

c ) Y only

d ) Z and X

Solution

Part 26

A convex  lens  of power 3 D. is held in contact with a concave lens of power -1D .At what distance from combination will beam get focused

a.  2 cm

b) 25 cm

c) 0.5 cm

d) 50 cm

Solution

Part 27

The velocity of light in a. glass is 2×10⁸ m/s in air is 3×10⁸ m/s .By how much an ink dot appears to be raised when covered by glass plate of 6 cm thick

a) 2cm

b) 4 cm

c) 6 cm

d) 1.5 cm

Solution.  (c)

Que 28

power of lens is -4D ,lens is

a) concave lens of focal length - 50 m

b) convex lens of focal length +50 cm

c) concave lens of focal length -25 cm

d) convex lens of focal length is + 25 cm

## NCERT solutions class 10th -Science- Acid Base and Salt

### Important Questions

Que 1
What are acid base indicators?

Ans
Acid base indicators are mixture of dyes which are used to indicate the presence of acids and bases

Que 2
What are properties of acid

Ans
Acids are sour in taste
Acid  change the colour of blue litmus to red
Whenever acids are dissolved in water they give H+ ion

Que 3
What are properties of a base

Ans
Bases are bitter in taste
Bases change the colour of litmus to blue
When bases dissolve in water they give hydroxyl ions (OH)-

Que 4
Name some natural indicators

Ans
Litmus  and turmeric

Que 5
Name some synthetic indicators

Ans
Methyl orange and phenolphthalein

Que 6
What is litmus solution

Ans
Litmus solution is a purple dye which is extracted from the lesson it is commonly used as an indicator litmus solution is neither acidic or basic its colour is purple

Que 7
Name some acid base indicators

Ans
Hydrangea ,petunia, Geranium

Que 8
If we have three test tubes one of them contains distilled water other two contains acidic solution and basic solution and if we have a litmus paper how will be identify the contents

Ans
we draw all the solutions and all test tubes one by one on the litmus paper

The solution which has no effect on litmus paper shows that this test tube contain distilled water

The solution which turns red litmus paper to blue colour it shows that the solution is basic solution

And the solution in the test tube which turns litmus paper blue colour to red it shows that the solution is acidic solution

Que 9
What is indicator

Ans
Indicator tell us whether a substance is acidic or basic by changing its colour

Que 10
What are olfactory indicators

Ans
There are substances whose odour changes in acidic and basic media these are known as olfactory indicators for example Vanilla onion

Que 11
What is neutralisation reaction

Ans
Acid and base react with each other to form salt and water is known as neutralization reaction

Acid +Base= Salt+ Water

Que 12
What are alkali

Ans
Bases which are soluble in water are called alkali they are so be to touch bitter and corrosive

Que 13
What is universal indicator

Ans
Universal indicator is a mixture of several indicators it shows different colours at different concentrations of hydrogen ions in a solution

Que 14
What is pH scale

Ans
Scale for measuring hydrogen ion concentration in solution is called pH scale

on pH scale we can measure pH generally from 0 to 14
pH of a neutral solution is 7
PH  less than  7  represents acidic solution
as the value of PH increases from 7 to 14 it represents increase in hydroxyl ion concentration in the solution presents basic solution

Que 15
What is brine solution

Ans
Aqueous solution of sodium chloride is called a brine solution

Que 16
Name the compound

a) used in soda acid fire extinguisher

Ans
Baking soda

b ) used to make drinking water free from germs

Ans
Bleaching powder

c) used to remove permanent hardness of water

Ans
Washing soda

d) used by doctors in treatment of fractured bones

Ans
Plaster of Paris

Que 17
What is the water of crystallization

Ans
What is the fixed number of water molecules present in one formula unit of a salt

Que 18
Name the acid which presence in the stomach of the human being

Ans
Hydrochloric acid

Que 19
PH value of element A is 5 and element Bis 12 which of them is acid and which of them is base

Ans
The elements which have PH value less than 7 are acidic in nature
The elements which have PH value greater than 7 and less than 14 are basic in nature

So element A  is acid where as element B is base

Que 20
In order to make dilute acid why we  not add water in acid

Ans
Acid are corrosive in nature so there must be a blast if we add water in acid so in order to make dilute acid we add acid in water drop voice drop

How to find PH

## IMPORTANT QUESTIONS

Que

Name the scientist who showed that an electricity and magnetism where related phenomena

Ans

Hans Christian oersted in 1820 discovered that a compass needle get deflected when an electric current pass through metallic wire in this way he show that electricity and magnetism where the related phenomena
That is arrested prove that whenever an electric current flows through a conductor it produces a magnetic field

Que

What is magnetic field

Ans

The region surrounding a magnet in which the force of magnet can be detected is said to have a magnetic field
Points to be noted
Magnetic field is a quantity that has has both direction and magnitude so it is a vector quantity
The direction of magnetic field is taken to the direction in which north pole of the compass needle moves inside it so we can say magnetic lines emerge from north pole and merge at South pole
Magnetic field lines are the closed curves
Magnetic field strength is a stronger generally at poles

Que

Why two magnetic field lines are never cross each other

Ans

Two magnetic field lines are never cross each other because if they ate it it would mean that at the point of intersection the compass needle would point towards two directions which is not possible

Que

What happens to deflection of the compass needle if the current in a wire is increased

Ans

If we increase the current in the wire the deflection in the needle increases

Que

What happens to the deflection of the needle if the compass is moved away from the wire but the current through the wire remains the same

Ans

If the compass is moved away from the wire but the current through the wire remains same the deflection in the needle decreases

Que

In order to find the direction of magnetic lines of field which rule can be used

Ans

In order to find the direction of magnetic lines of field right hand thumb rule is used according to this rule if you are holding a current carrying straight conductor in our right hand such that thumb point towards the direction of current then the fingers will wrap around the conductor in the direction of field lines of magnetic field for example if the current is in East West direction then with the help of right hand rule the magnetic field turn clockwise in a plane perpendicular to the wire when viewed from the east end but when viewed from the West end it appears anticlockwise

Que

Describe Maxwell for screw rule

Ans
According to this rule if we consider our self driving a for screw in the direction of the current in the direction of rotation of corkscrew is the direction of the magnetic field

Que

What is solenoid

Ans

Many circular coils of insulated copper wire wrapped closely in the shape of a cylinder is called a solenoid

Que

Describe the properties of magnetic field of lines inside the solenoid

Ans

The field inside the solenoid are in the form of parallel straight lines
What is magnetic field inside a solenoid is same at all the points or we can see that uniform magnetic field

Que

What is electromagnet

Ans

Electromagnet consists of a core of soft iron wrap around with a coil of insulated copper wire

Que

Name the scientist who suggested that magnet also exerts an equal and opposite force on the current carrying conductor

Ans

Andre Marie ampere suggested that a magnet also exert an equal and opposite force on the current carrying conductor you also shows that direction of force on the conductor depends upon the direction of current and direction of the magnetic field

Que

Describe Fleming's left hand rule

Ans

According to Fleming's left hand rule if we stress the term for finger and middle finger of our left hand such that they are mutually perpendicular to each other then the first finger points in the direction of magnetic field second finger in the direction of current and the thumb will point in the direction of the motion of the force acting on the conductor

Que

Describe Fleming right hand rule

Ans

According to Fleming right hand rule we can find the direction of the induced current if we stretch our power thumb 4 finger and middle finger of the right hand so that they are perpendicular to each other then the four finger indicates the direction of magnetic field some shows the direction of motion of conductor and the middle finger shows the direction of the induced current

Que

Name some devices that uses current carrying conductors and magnetic fields

Ans

Electric motor electric generator loudspeaker microphones

Que

What is MRI

Ans

Full form of MRI magnetic resonance imaging
The magnetic field inside the body forms the basis of obtaining the images of different body parts this is done using the technique MRI analysis of these images help in medical diagnosis

Que

What is electric motor

Ans

Electric motor is a rotating device that converts electrical energy to mechanical energy

Que

What is commutator? What is the role of a split ring in the electric motor

Ans

A device that reverse the direction of flow of current through a circuit is called commutator in electric motors the split ring acts as a commutator

Que

What is armature

Ans

A soft iron core on which soil is found plus the coils is called and armature

Que

What are the features of commercial motors

Ans

Commercial motors use
Electromagnet in place of permanent magnet
Large number of terms of conducting wire in the current carrying coil
Soft iron core on which the coil is wound

Que

Name the scientist who discovered that a moving magnet can be used to generate electric current

Ans

When a current carrying conductor placed in a magnetic field such that the direction of current is perpendicular to the magnetic field the conductor experiences of force it causes the conductor to move

Que

What is galvanometer

Ans

Galvanometer is an instrument that can detect the presence of current in a circuit deflect in the left or right to the zero mark depending upon the direction of the current

Que

What is electromagnetic induction

Ans

The production of induced current in a coil placed in a region where the magnetic field changes with the time  is called electromagnetic induction the magnetic field may change due to relative motion between coil and magnet placed near the coil

Que

What is electric generator

Ans

In an electric generator the mechanical energy is used to rotate a conductor in a magnetic field to produce electricity
With the help of electric generator we can obtain the alternating current in this generator the current changes its direction after equal intervals of time and we can get large current which we use in our homes and industry
Ac generator converts mechanical energy into electrical energy and it works on the basis of electromagnetic induction

Que

What is difference between alternating current and direct current

Ans

The direct current is the current which does not changes its direction with the time this is a unidirectional current and the generator from which way to cure the direct - current is called DC generator
And the current which changes its direction with the equal interval of time is called AC current

The main difference between direct and alternating current is that direct current always flows in one direction where is alternating current reverses its direction periodically

Que

What is the frequency of alternating current

Ans

50 Hz

Que

What is livewire

Ans

The wire in which there is a direct supply of electricity is called life fire it is always taken as positive generally its colour is red

Que

What is neutral wire

Ans

The neutral wire is generally taken as negative the wire having black insulation is termed as neutral wire

Que

What is the rating of current for the appliance having high power voltage such as geyser air cooler

Ans

15 A

Que

What is the rating of current for the appliances for fan, bulb

Ans

5 A

Que

Which wire is used as a safety measure for the appliances having a metallic body

Ans

Large wire which has the insulation of green colour is generally used as a safety measure it is usually connected to a metal plate deep in the earth near the house if there is any leakage of current to the metallic body of appliance then because of this wire the user may not get a severe  electric shot

Que

How the appliances are connected to each other in domestic  circuits

Ans

They are connected parallel to each other

Que

What is electric fuse

Ans

Electric fuse in a circuit prevents the damage to the appliance and the circuit due to overloading or short circuiting

Que

Ans

Overloading in the circuit generally occurs when the live wire and neutral wire come into direct is generally occurs when there in solution of the wire is damaged or there is a fault in the appliance

Que

What is short circuiting

Ans

Find the current in the circuit abruptly increases this is called short-circuiting

Que -- How domestic wiring is done in Homes

Solution

## NCERT solutions class 10- Effect of Current

### Important Questions

Que 1

Define electric current?

Ans

Current is the rate of flow of charge across a cross section normal to the direction of the flow of the current

Charge q flows across any cross section of a conductor in time t then the current is
I=Q/t = ne / t

Unit of current is ampere

Current is a scalar quantity

Unit of charge is coulomb

Que 2

Define 1 ampere?

Ans
1 ampere is constituted by the flow of one coulomb of charge per second

Que 3

Name the instrument used to measure the electric current?

Ans
Ammeter

Que 4

How the ammeter is connected in circuit?

Ans
Ammeter is always connected in series in the circuit

Que 5
What is the direction of electric current in a circuit

Ans
Electric current always flow from positive terminal to the negative terminal of the cell in a circuit

Que 6
What are number of electrons constituting one coulomb of charge

Ans
One coulomb of charge constitutes 6×10^18 electrons

Que 7
What is electric potential difference

Ans
Electric potential difference between two points in an electric circuit is the work done to move a unit charge from one point to another
Potential difference is denoted by v its SI unit is v named after alessandro Volta

V= W/Q

Concept of potential Difference

Que  8
Define one  volt

Ans
1 volt is a potential difference between two points in a current carrying conductor when one joule of work is done to move a charge of one column from one point to another

Que 9
In the instrument used to measure the potential difference in the circuit

Ans
Voltmeter

Que 10
How the voltmeter is connected in the circuit

Ans
Voltmeter is always connected in parallel across the points between which potential difference is to be measured in a circuit

Difference between voltmeter and ammeter

Que 11
Describe ohm's law

Ans
In 1827 a German physicist George Simon ohm found out a relationship between current flowing in a wire and a potential difference across its terminals

According to this law
The potential difference v across the ends of a given metallic wire in an electric circuit is directly proportional to the current flowing through it provided its temperature remains the same

V/I = constant

V/I = R

R is  a constant for the given metallic wire at a given temperature and it is called its resistance

Numericals on Ohms Law

Que 12
Define resistance

Ans
Resistance is the property of a conductor to resist the flow of charges through it unit of resistance is ohm

Que 13
How the current through a resistor
depends upon its resistance

Ans
The current through register is inversely proportional to its resistance
Is there is a sentence is double the current get halved

Que 14
What is rehostat

Ans
In an electric circuit it is a device used to change the resistance in the circuit

Que 15
On which factors the resistance of a conductor depends

Ans
Resistance of the conductor depends on following factors

Length
Resistance directly depends upon the length is the length increases then the resistance also increases

Area
Resistance of a conductor inversely proportional to area of cross section of the conductor if area of cross section increases then resistance decreases

Nature of the material of conductor

R=pl/A

P (rho)---  is a constant of proportionality and is called electrical resistivity of the material of the conductor its unit is ohm meter

Numerical on Resistance

Que  16
Name the element used as a filament in electric bulb

Ans
Tungsten

Que 17
Name the elements used for electric transmission lines

Ans
Copper and aluminium

Que 18
When the resistors are connected in series what is the formula for equivalent resistance and which quantity is constant in case of series arrangement

Ans
When resistors are connected in series
R= R1+R2+....

When the resistors are connected in series the current flowing through them is same

Que 19
Write the formula for equivalent resistance when the resistors are connected in parallel which quantity is constant in case of parallel arrangement

Ans
When the resistors are connected in parallel

1/R=1/R1+1/R2........

When the resistors are connected in parallel the potential difference between them is same

Que 20
What is electric power

Ans
The rate at which electric energy is dissipated or consumed in an electric circuit is termed as electric power

P=V×I
The SI unit of electric power is watt

Que 21
What is the commercial unit of electric energy

Ans
The commercial unit of electric energy is kilowatt hour which is commonly known as unit
1 kWh = 3.6 ×10^6 joule

Recorded lecture on heating effects of current

Que 22
What is joules law of heating

Ans
This implies that heat produced in a resistor is
directly proportional to the square of the current for the given resistance and also
it is directly proportional to the resistance for a given conductor
directly proportional to the time for which current flows through the resistor

H=I^2RT

Some more numericals---

Cell

In a cell chemical energy changes into electrical energy
A cell consists of a vessel containing two conducting rods called electrodes at some separation or  immersed in a solution called electrolyte

Constituents of cell

1) Two electrodes

2) electrolytes of cell

Cells are  of two types

1) primary cell

2) secondry cell

Primary cell

-- the chemical energy is converted into electrical energy when current is drawn from it

-- chemical reaction is irreversible

-- it cannot be recharged

Ex  dry cell  , voltaic cell

-- electrical energy conversion to chemical energy when current is passed in it while the chemical energy converted into electrical energy when current is drawn from it

-- chemical reaction is reversible

--- it can be recharged

Ex  Lead accumulator , Ni Fe accumulator

Exersices

1)
Name one DC source and one AC source

Ans -- DC source -- dry cell

AC - source -- Mains

Que --
what are conductors and insulators of electricity?

Ans --

Conductor -- substances through which electric current flows due to electrons is called good conductor for example copper

Insulator -- substances through which electric current does not flow is called insulator for example wood

Que--
Select conductors of electricity from the following

Copper wire, silk thread ,pure water acidulated  water, human body ,glass,
Mercury

Ans conductors --

Copper wire ,human body, Mercury ,acidulated  water

Que --

What is the difference between closed circuit and an open circuit

Closed circuit -- keys in a circuit are closed and the current flows through the circuit  it is called closed circuit

Open Circuit -- when keys in a circuit are open and the current does not flow through the circuit it is called open circuit

Que -- what is the function of key or switch in an electric circuit what is the condition required for circuit to be a closed circuit

Ans -- key of the switch in an electric circuit is used to put on or off the current in the circuit

For a circuit to be a closed circuit so that current flows in it he should be put on

Que --

Name the instrument used to control current in an electric circuit

Ans Rheostat

## Reflection of Light and Laws

Light is a medium which enables us to see
Light always travels in a straight line with a speed of 3×10^8m/s
Whenever light travels from one medium to another  three process occurs

Reflection

Refraction

Absorption

What is Reflection of Light

Light falls on boundry of medium returns back to the same medium it is known as reflection of light what is bouncing back of light rays and falling on a boundary of two medium is known as reflection of light
Laws of reflection

Incident ray reflected ray and normal all lie in the same plane

Angle of incidence is always equal to angle of reflection

Watch the attached lecture

when  light falls on convex mirror and concave mirror when light falls on convex mirror and concave mirror it behaves differently

We can find out the focal length concave mirror and the point where the images can be formed by using a  formula known as mirror formula

1/f=1/v+1/u

Where f is the focal length where is the distance of image and you is the distance where the object is placed in front of the mirror
The lecture attached given below explain different tricks and methods and question by which you can solve different types of numericals related with the minerals
Tricks to solve numericals on mirror

The mirror in which we see our images is known as plain  mirror images formed in a plane are laterally inverted that is right hand become left hand and left hand become right hand some properties of plane mirror which are very useful and and questions based on plane that are explained in the attached lecture
Plane Mirror and its numericals

What is Refraction of Light
Light goes from one medium to another speed gets changed because of the density of the particles which results in bending of path of light when goes from one medium to another
So whenever a light goes from one medium to another there is deviation of path which is known as refraction of light
Laws of refraction
The incident ray refracted Ray and the normal all lie in the same plane

The ratio of sin of incident ray and sin of reflected ray is always constant which is known as refractive index of the material
This law is also known as snell law
sin i/sin r=constant

Refraction through a glass slab
Light course home one medium to another for example when it goes from air to glass and then again glass to air it undergoes the process of refraction
Light goes from rarer to denser medium in banks towards the normal and when it goes from denser to rarer medium advance away from the normal it is because of these phenomena and life moves from air to glass and then again glass to air there is a later shift in the part of the life which is known as lateral displacement
The process of lateral  displacement is explain in the lecture attached given below

Refractive  Index

Refractive index is the ratio of speed of light in vacuum to speed of light in a medium
As it is ratio of same quantities its SI unit is zero

Different  questions based on the topic of refractive index are explain in the lecture attached will you must watch this lecture this is very important for the examination point of view

RAY DIAGRAM

Zombie bus from the heading ray diagram in the particular attached with you I explain how to learn and understand the ray diagrams by which we understand how the light  behaves when it travels from one medium to another what type of image is formed when light travels from air to glass through the lenses or  mirror

Numericals based on  Refraction  of lens
Lens formula
1/f=1/v-1/u

Questions based on magnification lens formula are explained in the lecture attached below us watch this picture because it is very helpful and solving your questions and different help books and NCERT I must ensure that you are watching this lecture you clearly understood how will you solve the questions based on the topic of lens

Magnification is the ratio of distance of image from the the lens to the distance of object from the lens
It is also equal to the ratio of height of the image to the height of the object

## NCERT solutions class 10th -Science- Heredity and Evolution

### Important Questions for CBSE Term 2- 2022

Monohybrid Cross

Sex Determination

Que
What is heredity

Ans
The transmission of genetically based characteristics from parents to the offspring is called heredity

Que
What are variations

Ans
Small differences among the individuals of the same species are called variations

Que
Who discovered the basic principles of genetics

Ans
Gregar John Mendel end of 19th century discovered the basic principle of genetics

Que
Which plant selected by Mendel for his experiments

Ans
Mental selected the garden pea ( pisum Sativum) for his experiments

Que
Why Mendel selected pea plant for his experiments

Ans
Mendel selected pea plant for his experiments because of following reasons

1) there are many varieties where available in alternative forms of character

2) varieties where available and pure forms that produce the same type of generation after generation

3) pea plant are self pollinated and could be as well as cross pollinated artificially

Que
What are the three mendel's law of inheritance

Ans
Mendel summarised his result known as mendel's law of inheritance

1) Law of Dominance
How does a pair of contrasting characters present together only one is able to express itself while the other remains suppressed

The character which expresses is called dominant character and the one which has unexpressed is called recessive character

2) Law of Segregation
The two members of a pair of factors separate during the formation of gametes

3) Law of independent assortment
There are two pairs of characters the distribution of the alleles of one character into the gametes is independent of the distribution of the alleles of other character

Que
What are autosomes

Ans
Autosomes are the kind of chromosomes which determine general body features like complexion height colour except on humans have 22 pairs of autosomes Human chromosomes are arranged in pairs in order of their size and shape known as karyotype

Que
What is sex chromosome

Ans
These are kind of chromosomes that determine the sex of an organism every human has only one pair of sex chromosome

Que
Describe the conditions when the child born is a son or a daughter

Ans
The sex of the child depends upon the kind of sperm that fertilizes the egg
Daya contains only X chromosomes but the response contains both X and y chromosomes

a) if the egg(X)  is fused by X bearing  sperm the resulting combination is XX the female constitution and the child born is a daughter

b) if the egg(X)  is fused by Y bearing  sperm the resulting combination is XY the male constitution and the child born is a Son
Or

The male cell  carries one X   and Y  chromosome where as female cell carries two XX chromosomes
The fusion of X chromosome bearing sperm of male cell with the X chromosome of female cell produces a female child
While the fusion of Y chromosome bearing sperm of male cell with  X chromosome of female  egg produces a male child

Therefore it is the contribution of father (sperm of male gamete) is determines the sex of newborn baby

Que
What are genes

Ans
It is a functional unit of heredity. That is present on the chromosome of cell nucleus characteristics which are transferred from parents to their offsprings generation to generation are controlled by genes during reproduction

Que
What do you mean by genotype

Ans
The set of genes present in the cells of an organisms. ie Genetic composition of an individual

Que
What is phenotype

Ans
The observable characteristics which are genetically controlled

Que
What do you mean by alleles

Ans
Every gene has two alternative forms for a character producing different effects these alternative forms are called alleles

Que
What is dominant Allele

Ans
The allele which expresses itself regardless of presence of another  allele is for a given gene. It is represented by capital letter TT

Que
What is recessive allele

Ans
The allele whose expression is suppressed in the presence of a dominant allele for a given gene It is represented by small letter Tt

Que -- Define homogygous?

Ans
Condition in which one individual causes a pair of identical dreams controlling a given character that is occurrence of two identical It  can be represented as TT

Que -- Define Heterogygous ?

Ans - condition in which an individual as a pair of contrasting jeans for any character that has existence of dominant and recessive alleles simultaneously .It can be represented as Tt

Que
What is monohybrid cross

Ans
Mendel cross to pure breeding varieties of pea plant by taking contrasting characters of one single character this is known as monohybrid cross

Que
What is dihybrid cross

Ans
Mendel cross to pure breeding varieties of pea plant by taking contrasting  two different characters is called dihybrid cross

Que
What do you mean by F1 generation

Ans
When two homozygous pea  plants with contrasting traits are crossed a heterozygous hybrid plant is obtained this is known as F1 generation

Que
What is F2 generation

Ans
When two hybrid plants of F1 generation are self crossed we obtain F2 generation

Que
What is the phenotypic monohybrid ratio in F2 generation

Ans.
The phenotypic monohybrid ratio is 3:1

Que

What is the phenotypic  dihybrid ratio in F2 generation

Ans
The dihybrid ratio in F2 generation
9:3:3:1

## NCERT solutions class 10th -Science- Reproduction

### Important Question

Que
What are the two methods of reproduction

Ans
There are two methods of reproduction
Asexual
Sexual

Que
What do you mean by asexual reproduction

Ans
Reproduction in which only one parent is involved is known as asexual reproduction

Que
What do you mean by sexual reproduction

Ans
Reproduction in which both parents are involved is known as sexual reproduction

Que
What do you mean by fission

Ans
The splitting of nucleus is to two parts is known as binary fission

Que
Which type of reproduction is found in unicellular organisms like amoeba

Ans
Amoeba

Que
Which type of reproduction is observed in yeast

Ans
Budding
In the process of budding but develops as an outgrowth due to repeated cell division at one specific site These buds was developed in tiny  individuals and when fully mature detached from the parent body and become new independent individuals
It is also observed in case of budding

Que
What do you mean by fragmentation

Ans
cell breaks up into smaller pieces upon maturation please pieces of fragments grow into new individuals this is known as fragmentation this type of reproduction is find in spirogyra

Que
What do you mean by vegetative propagation

Ans
new plants develop from any parts of the plant like stem leaves root it is known as vegetative propagation for example sugarcane and rose

Que
Name different parts of the flower

Ans
Different parts of the flower are
Sepal Petal stamens and pistil
Watch the lecture
Reproduction in Flower

Que
What is pollination

Ans
Transfer of pollen grains from anther to the stigma is called pollination

Que
What is germination

Ans
The seed  contains embryo develops into a seedling under appropriate conditions this process is known as germination

Que
Name the hormone which brought changes in two boys at the  time of puberty

Ans
Testosterone

## NCERT solutions class 10th -Science- Life Process

Que
What are the autotrophic nutrition

Ans
Intake of simple inorganic materials from the environment and using an external energy source like the sun to synthesise complex high-energy organic material is called autotrophic nutrition

Why sunlight is necessary for the photosynthesis
what's the lecture

Why chlorophyll is necessary for photosynthesis

Que
What is heterotrophic nutrition

Ans
It involves intake of complex material prepared by other organisms

In order to understand heterotrophic nutrition watch the lecture

Que
Why single celled organisms require no specific organs for taking in food

Ans
Single celled organisms no specific organs for taking in food exchange of gases or removal of wastage from the body may be needed because the entire surface of the organism is in contact with the environment

Que
What is stomata

Ans
The tiny pores present on the surface of the leaves is called stomata the gaseous exchange takes place in the leaves through this pores

Que
What are guard cells

Ans
Opening and closing of stomata is a function of guard cell the guard cell swell when the water flows into them and causing the stomatal pore to open while the pore close when   a guard cell shrink

Watch the Lecture to know about stomata

Que
How does nutrition in amoeba takes place

Ans
The single celled organism amoeba takes nutrition by the process known as pseudo pedia

Order to understand the whole process watch the whole educational lecture

Que
How respiration in the plants occur

Ans
Plants respire generally through stomata in some cases it also has fire to lenticels present in the stem in order to understand what the lecture given below

Que
What is breathing

Ans
Intake of Oxygen and exhale of carbon dioxide from the nostrils is known as breathing

Que
What is the difference between respiration and breathing

Ans
Breathing is only intake of Oxygen and exhale of carbon dioxide from the nostril but on the other hand respiration is the conversion of glucose into energy in form of ATP using the oxygen

## Important questions

Que 1
How many elements are known to us

Ans
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

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