UPSC CSE Prelims
Question 91
Consider the following pairs:
| Objects in space | Description |
|---|---|
| 1. Cepheids | Giant clouds of dust and gas in space |
| 2. Nebulae | Stars which brighten and dim periodically |
| 3. Pulsars | Neutron stars that are formed when massive stars run out of fuel and collapse |
How many of the above pairs are correctly matched?
View correct answer and explanation
Correct answer: A
Correct Option: A (Only one)
Explanation: Cepheids are pulsating variable stars, nebulae are gas/dust clouds, and pulsars are rapidly spinning magnetized neutron stars; only the third pairing is correct.
Statement / Pair / Item-wise Analysis:
1. Incorrect/False - Cepheids are variable stars with periodic changes in brightness, not clouds of dust and gas.
2. Incorrect/False - Nebulae are interstellar clouds of gas and dust, not pulsating stars.
3. Correct/True - Pulsars are rotating neutron stars, often remnants of core-collapse supernovae.
Option-wise Analysis:
A. Correct-exactly 1 of the 3 listed items satisfy the condition.
B. Incorrect-it counts 2, but only 1 qualify; item(s) 1, 2 do not.
C. Incorrect-it counts 3, but only 1 qualify; item(s) 1, 2 do not.
D. Incorrect-it counts 0, but items 3 qualify, giving 1.