41). Assertion (A) : Woollens keep us warm.
Reason (R ) : Wool fibres are made of a particular protein which is a bad conductor of heat.
| 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. |
|
42). Assertion (A) : Fatty acids should be a part of the balanced human diet.
Reason (R ) : The cells of the human body cannot synthesize any fatty acids.
| 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. |
|
43). Assertion (A) : Natural selection maintains and propagates the beneficial genes while limiting harmful ones in a particular environment.
Reason (R ) : There are genes which are responsible for the production of beneficial characters while others are harmful.
| 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. |
|
44). Assertion (A) : Sounds carry farther at night than during a sunny day.
Reason (R ) : During the day, air near the ground is warmer than the air above.
| 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. |
|
45). Assertion (A) : The spleen helps the body fight infection.
Reason (R ) : The spleen stores red blood cells.
| 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. |
|
46). Assertion (A) : In our houses, the current in electricity line changes direction 60 times per second.
Reason (R ) : The frequency of alternating voltage supplied is 60 hertz.
| 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. |
|
47). Assertion (A) : Photographs taken through a microscope are often taken by short-wavelength ultraviolet.
Reason (R ) : Resolving power is increased by using illumination of shorter wavelength.
| 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. |
|
48). Assertion (A) : An incandescent lamp has a tungsten filament.
Reason (R ) : Tungsten is a very good conductor of electricity.
| 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. |
|
49). Assertion (A) : Cordless telephone is a wireless version of a conventional telephone.
Reason (R ) : Most cordless telephones operate only within a range of a few hundred metres.
| 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. |
|
50). Assertion (A) : A black hole is an astronomical body that can not be seen.
Reason (R ) : The gravitational field on a black hole is so strong that it does not allow light to escape.
| 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. |
|
