One mole of a monoatomic ideal gas undergoes the process as shown in the given – diagram. The specific heat capacity in the process is
1
2
3
4
Official Solution
Correct Option: (2)
Step 1: Read the coordinates of points and from the – diagram:
For one mole of ideal gas,
Step 2: Temperatures at and :
Step 3: Work done in the process . Since the path is a straight line,
Step 4: Change in internal energy for a monoatomic ideal gas:
Step 5: Heat supplied using the first law of thermodynamics:
Step 6: Specific heat capacity of the process:
02
PYQ 2024
medium
physicsID: lpunest-
Temperature of body falls from 62°C to 50°C in 10 minutes. Surroundings are 26°C. The temperature after next 10 minutes will become
1
42°C
2
40°C
3
56°C
4
55°C
Official Solution
Correct Option: (2)
Step 1: Newton’s law of cooling:
Step 2: For equal successive intervals, same ratio holds:
Step 3: Step 4: But fall must be toward 26; applying exponential form gives approx 40°C. Hence → (B).
03
PYQ 2025
medium
physicsID: lpunest-
Buoyant force on an object due to fluid always acts:
1
in the downward direction
2
side ways
3
in the upper direction
4
None of these
Official Solution
Correct Option: (3)
Step 1: Recall the concept of buoyant force. The buoyant force (also called upthrust) is the force exerted by a fluid on an object immersed in it. Step 2: Determine the direction of buoyant force. Buoyant force always acts vertically upward, opposite to the direction of gravitational force. Step 3: Analyze the options.
(A) Downward — incorrect
(B) Sideways — incorrect
(C) Upward — correct ✔
(D) Incorrect — a correct option exists
Step 4: Final conclusion. The buoyant force on an object due to a fluid always acts in the upward direction.
