In India, flood forecasting and warning is the responsibility of which organisation?

The correct answer is B, epicentre. The energy of an earthquake is released at a point inside the earth, and the point on the surface directly above it is the epicentre, where the tremor is felt first and usually most strongly; it is the point reported in news bulletins. A is wrong because the focus, also called the hypocentre, is that place of origin inside the earth, not on the surface, and the depth of the focus decides whether an earthquake is shallow, intermediate or deep. C is wrong because a fault line is the fracture in the crust along which the rocks move, and it may run for hundreds of kilometres, while the epicentre is a single point. D is wrong because a seismic belt is a broad zone such as the Circum-Pacific belt where earthquakes are concentrated, which is a regional idea and not a point.

The correct answer is C, the Richter scale. It expresses magnitude, the energy released at the focus, on a logarithmic scale, so a rise of one whole number means about thirty-two times more energy, and a single earthquake has only one magnitude whatever the distance of the observer. A is wrong because the Modified Mercalli scale measures intensity, the shaking and the damage actually felt at a place, so the same earthquake has a high Mercalli value near the epicentre and a low one far away. B is wrong because the Beaufort scale describes wind speed by its visible effects on the sea and on land. D is wrong because the Saffir-Simpson scale classifies hurricanes by their wind speed into categories one to five. Magnitude with Richter and intensity with Mercalli is the pair examiners want.

The correct answer is B, secondary waves. S waves are transverse: the particles move at right angles to the direction of travel, and that requires a medium with shear strength, which liquids do not have. The shadow zone created by the failure of S waves to cross the outer core is the evidence that the outer core is in a liquid state. A is wrong because P waves are longitudinal, travel as a push and pull along the direction of motion, move fastest and pass through solids, liquids and gases, which is why they are the first to be recorded on a seismograph. C is wrong because surface or L waves travel along the surface of the earth, are the slowest and cause the greatest destruction to buildings, but they do not travel through the body of the earth at all. D is therefore wrong as well.

The correct answer is B, four zones numbered II to V. The earlier Zone I was merged with Zone II, so the map now runs from Zone II, of low hazard, to Zone V, of the highest hazard, which covers Kutch, the Andaman and Nicobar Islands, most of the North-East, parts of northern Bihar and parts of the western Himalaya. A is wrong because three zones never formed the Indian classification. C is a deliberate distractor built on the old numbering: five zones from I to V belong to the superseded map, and marking it is the commonest error in this question. D is wrong because no Indian zoning map has six classes. Remember that the number of zones is four while the highest number used is five, which is exactly the confusion examiners exploit.

The correct answer is B, 2005. The Disaster Management Act, 2005 set up the National Disaster Management Authority, the State Disaster Management Authorities and the District Disaster Management Authorities, and provided for the National Disaster Response Force and the National Institute of Disaster Management. A is wrong because 2001 is the year of the Bhuj earthquake in Gujarat, which, with the super cyclone of 1999 and the tsunami of 2004, created the pressure for such a law, but no Act was passed that year. C is wrong because 2009 is the year of the National Policy on Disaster Management, a policy document issued under the Act and not the Act itself. D is wrong because 2015 is the year the Sendai Framework for Disaster Risk Reduction was adopted internationally, which is a global agreement rather than Indian legislation.