Which of the following is not correct?

Answer: (b) Hurricane - A wind having a mean velocity of less than 100 km per hour

Not correct — a hurricane has winds of 118 km/h or more, not less than 100.

The idea

A hurricane is a tropical cyclone that has reached hurricane-strength sustained winds. Its classification depends on measured wind speed, rather than on the size of the eye or the amount of rain. Atlantic and eastern North Pacific hurricanes begin at about 119 km/h, well above 100 km/h.

Why the others are wrong

(a) Correct — the doldrums are the equatorial low.

(c) New Moore (South Talpatti) was claimed by India (it has since sunk).

(d) The Rann of Kutch has alluvial and marine deposits.

Elimination technique

The sustained-wind threshold for a hurricane is already above 100 km/h. That directly disproves (b), which is sufficient in a question asking for the incorrect pair.

Also know

Hurricane, typhoon and cyclone are regional names for the same broad kind of rotating tropical storm. The eye can be calm, but the surrounding eyewall has intense winds and rain. Doldrums refer to the equatorial low-pressure belt with generally weak surface winds; alluvium means sediment deposited by flowing water. New Moore was a former sandbar in the Bay of Bengal and later disappeared beneath the sea.