CSIR NET 2024 Physical Science Previous Year Paper (25-July-2024)

Question 1

A large number of birds, half of which belong to specie A and the other half to specie B, rest on a tree where they are distributed randomly across the branches. In a random sample of 5 birds from the tree, what is the probability that at least one is from specie A?

Accepted Answer

0.96875

Answer

0.03125

Answer

0.15625

Answer

0.84375

Question 2

Suppose that the increase in a population can be modelled as$\left( \frac{dN}{dt} \right) = rN \left( \frac{K - N}{K} \right)$where N is the size of the population, K is the carrying capacity, r is the per capita growth rate and t is time. Which of the following statements is correct?

Accepted Answer

When N ≈ 0, the change in population N is nearly exponential.

Answer

When N = K, the population goes extinct as dN/dt goes to zero.

Answer

When N ≈ 0, the population growth dN/dt is maximum.

Answer

When N ≈ K/4, the population growth dN/dt is maximum.

Question 3

A rectangular tray of 30 cm x 60 cm size is used for baking circular biscuits. The diameter of each biscuit is 3 cm before baking, which increases by 10% on baking. What is the maximum number of biscuits that can be baked in the tray such that the base of each biscuit is in contact with the tray?

Accepted Answer

162

Answer

171

Answer

180

Answer

200

Question 4

In how many distinct ways can 128 identical marbles be arranged in a complete rectangular grid (disregarding the orientation of the grid)?

Accepted Answer

4

Answer

7

Answer

6

Answer

5

Question 5

How many three-digit numbers exist whose first and last digits add up to 9?

Accepted Answer

90

Answer

81

Answer

80

Answer

72

CSIR NET 2024 Physical Science Previous Year Paper (25-July-2024)

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