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?
Show answer
Answer: A. Pair 1 is wrong: Cepheids are stars that brighten and dim at regular intervals. Pair 2 is wrong: nebulae are giant clouds of dust and gas. The descriptions of 1 and 2 are swapped. Pair 3 is correct: pulsars are rotating neutron stars formed when massive stars collapse. So only one.
Watch for: The descriptions are correct facts, just attached to the wrong objects.
Why the other options are wrong
- B. Wrong because pairs 1 and 2 have their descriptions swapped.
- C. Wrong because Cepheids and nebulae are wrongly matched.
- D. Wrong because the pulsar pair is correct.
Source to check: NASA Science website (Cepheid variables, nebulae, neutron stars and pulsars)
Answer from the official UPSC key. Written and fact-checked by AI against the official key. Spotted a mistake? Report it.