26: Assertion (A) :
A man standing on a completely friction-less surface can propel himself by whistling.
Reason (R) :
If no external force acts on a system, its momentum cannot change.
(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
27: Consider the following specific stages of demographic transition associated with economic development :
1. Low birthrate with low death rate
2. High birthrate with high death rate
3. High birthrate with low death rate
Select the correct order of the above stages using the codes given below :
(a) 1, 2, 3
(b) 2, 1, 3
(c) 2, 3, 1
(d) 3, 2, 1
28: Assertion (A):
Fatty acids should be apart of the balanced human diet.
Reason (R):
The cells of the human body cannot synthesize any fatty acids.
(a) Both A and R are individually true and R is the correct explanation of A
(b) Both A and R are individually 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: Which of the following is a balanced fertiliser for plants?
(a) Urea
(b) Ammonia sulphate
(c) Nitrates
(d) Compost
30: Which of the following pairs is/are correctly matched ?
Inventor : Invention
1. Christopher : Hovercraft Cockerell
2. David Bushnell : Submarine
3. J.C. Perrier : Steamship
Select the correct answer using the code given below :
(a) 1 and 2, only
(b) 2 and 3, only
(c) 1 and 3, only
(d) 1, 2 and 3