1.b

Escape velocity of earth is 11.2km/s

2. d

The image of nearer object formed by a long sighted person
is behind the retina. Convex lens is used for remedy.

Cause:
1. Increase in focal length of eye

2. Contraction of eye ball.

Whereas the image of far object formed by a short sighted
person is in front of the retina. Concave lens is used for remedy.

Cause:
1. Decrease in focal length of eye

2. Elongation of eye ball.

3. C

Splitting of beam of light is called dispersion.

White light splits into 7 colors .i.e VIBGYOR

Polarization: restricting vibrations of wave in a single
plane.

Deviation: bending of light when travels from one medium to
another.

4. D

When placed in contact , effective power of system is the
sum of individual power of lenses.

i.e P=P1+P2

Sign should be considered.

5. A

Light year is the unit of distance.

It is the distance travelled by light in a year.

1 light year= 9.460536207×1015 m

6. D

Total heat= 720 calories

Latent heat of fusion=80 calories

It is the heat to convert ice from 0 degree to water at 0 degree

Latent heat of vaporization=540 calories

It is the heat to convert water from 0 degree to vapor at
100 degree

Heat required to convert 1gm of water from 1°C to 100°C =
100 calories

Total heat =Sum of all these three.

7. D

In projectile,

Acceleration/retardation, total energy remains constant.

Velocity, kinetic energy, momentum decreases until the top
height and in falling down they increase.

Potential energy increases with height.

8. A

Weight is more in polar region but mass is same everywhere.

Value of g is more in polar region than equatorial region.

Weight=mg

9. B

1 calorie = 4.2 Joule

1 Joule=1/4.2 calorie

10. A

The field of view is maximum for convex mirror and least for
concave mirror.

Concave mirrors are used in shaving, ophthalmoscope and
cinema projectors.

Convex mirror is used in vehicle.

11. c

Efficiency=MAVR*100%

=6/12*100%

=50%

12. a

For equilibrium of three forces the sum of any of two forces
must be equal to or more than the remaining third force.

So, only 10N, 12N, 25N set of forces cannot be in equilibrium.

13. a

Intensive property

It doesn't depend upon quantity

e.g. Temperature, Density, Refractive

Index, Specific heat, surface tension, boiling point,
melting point

Extensive property

It depends upon the quantity.

e.g. Thermal capacity, Pressure, Volume, Mass, free energy
etc.

14. b

Intensity of sound is more in night due to increase in
density.

carbon dioxide gets concentrated near ground so, density
increases and sound intensity increases.

15. b

Minimum size of mirror to see full image of oneself is Half
of observer

16. b

Application of total internal reflection:

Mirage

Looming- mirage in cold area

Brilliance of diamond

Optical fiber, endoscopy

Air bubbles appearing silvery white inside water.

Rainbow (due to dispersion as well)

17. b
Protein coat of virus is capsid and it is made up of capsomeres.

18. a

Small pox is caused by Variola virus.

Other viral diseases

Vericella virus- Chicken Pox

Polio virus- Polio

Rhinovirus- Common cold

Morbillivirus- Measles

HIV- AIDS

COVID 19- corona

19. b

In Meiosis I number of chromosome reduces to half in
daughter cell.

20. a

Replication of DNA
takes place in Interphase.

It has 3 sub-phases.

synthesis of structural and functional proteins, Ribosomes
mitochondria, chloroplast, lysosome,

golgi-complex etc. occurs

Nucleolus produces r RNA, t RNA and mRNAs

2. Synthesis (S) phase-DNA synthesis phase

DNA replication takes place.

Synthesis of histone protein occurs.

3. Gap two (G2) Phase-

centriole replicates

spindle and aster proteins are formed

Energy storage takes place,

spindle fiber begins to form.