31: Gypsum is added to the soil?
(a) To increase the alkalinity
(b) To decrease the acidity
(c) To decrease the alkalinity
(d) As an insecticide
32: Sugarcane, sugarbeet, sweetpea, chickpea, pigeonpea and French bean belong to
(a) two plant families
(b) three plant families
(c) four plant families
(d) five plant families
33: The human immuno deficiency virus (HIV) is a living entity because it can
(a) Excrete in human serum
(b) Disturb host cell respiration
(c) Undergo auto-reproduction
(d) Move from one cell to another
34: Assertion (A) :
In a motion picture, usually 24 frames are projected every second over the whole length of the film.
Reason (R) :
An image formed on the retina of eye persists for about 0.1 s after the removal of stimulus.
(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 a correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
35: Mixed cropping is useful when:
(a) Crops with varying maturity periods are sown together
(b) Crops with same maturity period are sown together
(c) Different soils are used for the same crops
(d) Crops with different nutritional requirements are grown