UPPCS Prelims 2018 · GS Paper I: The maximum concentration of ozone is found in which of the following ?
The maximum concentration of ozone is found in which of the following ?
Answer (c) & explanation
Option (c) is right: about 90 per cent of the atmosphere's ozone is in the stratosphere, mostly between about 15 and 35 km above the surface, where it forms the ozone layer that absorbs harmful ultraviolet-B radiation. Option (a), the troposphere, has only a small amount of ozone, mostly ground-level ozone formed in smog, which is a pollutant. Option (b), the mesosphere, and option (d), the exosphere, have very little ozone. Concept: ozone is depleted by chlorofluorocarbons and halons, which release chlorine and bromine; this caused the Antarctic ozone hole. The Montreal Protocol of 1987 phased out such substances, and the Kigali Amendment of 2016 added hydrofluorocarbons. 16 September is World Ozone Day. Ozone is measured in Dobson units.
Most weather happens in the troposphere, but the ozone layer is in the stratosphere.
Question as printed in UPPSC's official question booklet. Source: uppsc.up.nic.in
Related questions from other years
Which of the following with reference to Indian States is/are not correct ?
- 1. Uttar Pradesh shares its boundary with the highest number of other Indian States.
- 2. Rajasthan shares the longest international border among all Indian States.
- 3. Sikkim is the only State that shares its boundary with just one other Indian State.
Select the answer using the code given below :
Answer (c) & explanation
Statements 2 and 3 are not correct (c). Statement 1 is correct: Uttar Pradesh touches eight States, plus Delhi, the most of any State. Statement 2 is wrong: the longest international border belongs to West Bengal, with Bangladesh, not Rajasthan. Statement 3 is wrong: Sikkim touches only West Bengal, but Meghalaya also touches only one State, Assam, so the word "only" fails. So options (a), (b) and (d) fail.
Notice the trap: the question asks which are not correct. UP's neighbours are Uttarakhand, Himachal, Haryana, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand and Bihar. Rajasthan has the longest border with Pakistan, about 1,070 km. Words like "only", "all" and "never" often hide the error.
The question asks for statements that are not correct. Statement 3 is half right; the word "only" breaks it.
Answer as per the official UPSC answer key.
Ships from which of the following countries have to cross the Strait of Hormuz to reach out to the Indian Ocean ?
- 1. Bahrain
- 2. Syria
- 3. Qatar
- 4. Egypt
Select the answer using the code given below :
Answer (b) & explanation
Bahrain and Qatar must cross the Strait of Hormuz (b). The Strait of Hormuz, between Iran and Oman, is the only sea exit from the Persian Gulf. Items 1 and 3 are right: Bahrain and Qatar lie wholly inside the Gulf, so their ships must pass it. Item 2 is wrong: Syria is on the Mediterranean. Item 4 is wrong: Egypt reaches the Indian Ocean through the Suez Canal and the Red Sea. So options (a), (c) and (d) fail.
Notice its importance: about a fifth of the world's oil passes through Hormuz, and much of India's crude and LNG (Qatar is a top LNG supplier). Iran's threats to close it raise prices. The UAE's pipeline to Fujairah and Saudi pipelines to the Red Sea help bypass it.
Answer as per the official UPSC answer key.
Tungurahua Volcano, which was declared a Global Geopark by UNESCO in 2025, is situated in which one among the following countries ?
Answer (a) & explanation
Tungurahua is in Ecuador (a). Tungurahua, meaning "throat of fire", is an active stratovolcano in the Andes of central Ecuador, above the town of Baños. UNESCO named the area around it a Global Geopark in 2025. Options (b), (c) and (d), Peru, Bolivia and Colombia, are wrong, though the Andes pass through all of them too.
Notice Ecuador's other famous volcanoes: Cotopaxi, one of the highest active volcanoes, and Chimborazo, whose summit is the point farthest from Earth's centre, because of the equatorial bulge. Ecuador also owns the Galápagos Islands. A Global Geopark honours geological heritage; India has none yet, though sites like Lonar have been proposed.
Answer as per the official UPSC answer key.
With reference to the climate of Andaman and Nicobar Islands, which of the following statements is/are correct ?
- 1. The climate can be defined as a humid, tropical coastal climate.
- 2. It receives rainfall from both South-west monsoon and North-east monsoon.
- 3. Maximum precipitation is between December and May.
Select the answer using the code given below :
Answer (b) & explanation
Statements 1 and 2 are correct (b). Statement 1 is right: the islands lie close to the equator in the Bay of Bengal, so they are hot and humid all year, a tropical coastal climate. Statement 2 is right: they get rain from both the south-west and north-east monsoons, from about May to December. Statement 3 is wrong: January to April is the driest part of the year, so maximum rain is not between December and May. So options (a), (c) and (d) fail.
Notice the islands' features: Barren Island, India's only active volcano; Saddle Peak, the highest point; and Indira Point, India's southernmost tip. Rich tropical evergreen forests cover them, and cyclones often form nearby.
Answer as per the official UPSC answer key.