21). Assertion (A) : When a wheel is in motion, a point (on the rim) which is farthest away from the ground will have the highest speed while the point (on the rim) closed to the ground will have the lowest speed.
Reason (R ) : The speed of the point on the rim in the direction of motion and along the circumference of the wheel are additive.
| A). Both A and R are true and R is the correct explanation of A. |
| B). Both A and R are true but R is not the correct explanation of A.. |
| C). A is true but R is false. |
| D). A is false but R is true. |
|
22). Assertion (A) : Some plants flower only during spring season.
Reason (R ) : Day length affects flowering in plants.
| A). Both A and R are true and R is the correct explanation of A. |
| B). Both A and R are true but R is not the correct explanation of A.. |
| C). A is true but R is false. |
| D). A is false but R is true. |
|
23). Assertion (A) : The flash of lightning is seen before the sound of thunder is heard.
Reason (R ) : The sound of thunder is produced after the flash of lightning.
| A). Both A and R are true and R is the correct explanation of A. |
| B). Both A and R are true but R is not the correct explanation of A.. |
| C). A is true but R is false. |
| D). A is false but R is true. |
|
24). Assertion (A) : The main source of energy in most of the Indian diets is carbohydrate.
Reason (R ) : Carbohydrate provides more energy per gram than proteins and fats.
| A). Both A and R are true and R is the correct explanation of A. |
| B). Both A and R are true but R is not the correct explanation of A.. |
| C). A is true but R is false. |
| D). A is false but R is true. |
|
25). Assertion (A) : Most of the time individual rain drops hit the earth's surface with constant velocities.
Reason (R ) : When an object falls through a viscous fluid, it attains a constant terminal velocity after sometime.
| A). Both A and R are true and R is the correct explanation of A. |
| B). Both A and R are true but R is not the correct explanation of A.. |
| C). A is true but R is false. |
| D). A is false but R is true. |
|
26). Assertion (A) : Dry battery cannot be recharged.
Reason (R ) : The chemical reaction is reversible.
| A). Both A and R are true and R is the correct explanation of A. |
| B). Both A and R are true but R is not the correct explanation of A.. |
| C). A is true but R is false. |
| D). A is false but R is true. |
|
27). Assertion (A) : Ventilators are provided near the roof.
Reason (R ) : Conduction takes place better near the roof.
| A). Both A and R are true and R is the correct explanation of A. |
| B). Both A and R are true but R is not the correct explanation of A.. |
| C). A is true but R is false. |
| D). A is false but R is true. |
|
28). Assertion (A) : There is no vaccine for AIDS.
Reason (R ) : The AIDS virus changes its genetic code.
| A). Both A and R are true and R is the correct explanation of A. |
| B). Both A and R are true but R is not the correct explanation of A.. |
| C). A is true but R is false. |
| D). A is false but R is true. |
|
29). Assertion (A) : Eggs of mosquitoes being very light in weight, float on water in water bodies.
Reason (R ) : Surface tension of water balances the weight of eggs.
| A). Both A and R are true and R is the correct explanation of A. |
| B). Both A and R are true but R is not the correct explanation of A.. |
| C). A is true but R is false. |
| D). A is false but R is true. |
|
30). Assertion (A) : A thin layer of oil on water shows beautiful colours when illuminated by white light.
Reason (R ) : Light waves reflected from the upper and lower surface of the thin layer interfere.
| A). Both A and R are true and R is the correct explanation of A. |
| B). Both A and R are true but R is not the correct explanation of A.. |
| C). A is true but R is false. |
| D). A is false but R is true. |
|
