Sandstone is an example of:

The correct answer is A, Loo. The loo is a hot, dry wind that blows over the plains of north India and Pakistan in May and June, often pushing afternoon temperatures above 45 degrees Celsius and causing heat strokes. Winds are grouped as planetary, which blow across the globe all year, seasonal, which reverse with the seasons, and local, which affect a small area for a short period because of local heating and pressure differences. Other local winds worth remembering are the chinook of North America, the foehn of the Alps, the mistral of France and the sirocco of the Mediterranean. Option B is wrong because the westerlies are planetary winds blowing from the subtropical high towards the subpolar low. Option D is wrong because the easterlies, or trade winds, are also planetary winds moving towards the equator. Option C is wrong because the monsoon is a seasonal wind that reverses direction between summer and winter. Exam tip: loo, chinook, foehn, mistral and sirocco are the standard local winds.

The correct answer is C, Mexico. Milpa is the name given to shifting cultivation in Mexico and in the neighbouring parts of Central America, where maize, beans and squash are grown together on a patch cleared from the forest. In shifting cultivation a plot is cleared by cutting and burning the trees, cropped for two or three years until the ash-fed soil loses its fertility, and then left fallow while the farmer moves to a fresh patch. Because the same practice grew up in forest belts across the world, it carries a different local name in each region. A is wrong because in India it is called jhum in the north-east, podu in Andhra Pradesh and bewar or dahiya in Madhya Pradesh. B is wrong because in Malaysia and Indonesia it is known as ladang. D is wrong because in Brazil it is called roca or coivara. Exam tip: milpa in Mexico, ladang in Malaysia, roca in Brazil, chena in Sri Lanka and jhum in north-east India.

The correct answer is B, Gerusoppa. The Sharavati river in Karnataka falls from a height of about 253 metres as Jog Falls, which is also called Gerusoppa Falls after the village nearby, and Jogada Gundi in the local tongue. It is among the highest plunge waterfalls in India, and the water comes down in four separate streams named Raja, Rani, Roarer and Rocket. The Linganamakki dam upstream now controls the flow, so the falls are at their finest during the monsoon. Option A is wrong because Hogenakkal is on the Kaveri in Tamil Nadu, close to the Karnataka border. Option C is wrong because Soochipara, or Sentinel Rock falls, is on the Chaliyar in Wayanad, Kerala. Option D is wrong because Athirappilly is on the Chalakudy river in Kerala and is called the Niagara of India. Exam tip: the Sharavati makes Jog or Gerusoppa Falls in Karnataka, while the Kaveri makes Hogenakkal and Shivanasamudra.

The correct answer is C, 15. The Planning Commission divided India into 15 agro-climatic zones in 1989, so that farm planning could follow soil, climate, rainfall and water resources rather than State boundaries. The zones run from the Western Himalayan Region and the Trans-Gangetic Plains to the East Coast Plains and Hills, the Western Dry Region and the Islands Region. The idea was to match crops and cropping patterns to the land, and it is still the base on which farm research and extension work are planned. Option A is wrong because 20 is not the Planning Commission's figure. Option B is wrong because 10 is too few and matches no such classification. Option D is wrong because 30 confuses this division with the far larger number of agro-climatic sub-zones worked out by the ICAR. Exam tip: the Planning Commission marked 15 agro-climatic zones in 1989, while the ICAR uses 127 agro-climatic sub-zones.

The correct answer is C, The air always moves from high pressure areas to low pressure areas. Air flows from where pressure is high to where it is low, and that moving air is what we call wind; the greater the difference in pressure, the stronger the wind. The Coriolis force then bends this flow, to the right in the Northern Hemisphere and to the left in the Southern. Option A is wrong because high pressure means sinking air, which brings clear skies and dry weather. Option B is wrong because low pressure means rising air that cools and condenses, so it brings clouds and rain. Option D is wrong because air pressure is highest at sea level, about 1,013 millibars, and falls as one goes up and the air thins. Pressure is measured with a barometer and shown on weather maps by isobars, the lines joining places of equal pressure. Exam tip: high pressure means sinking air and clear weather; low pressure means rising air, clouds and rain.