Questions

The weight of the man mg is acting on the floor. As the lift is moving up with an acceleration, say a, the man too in it is having this acceleration. The force producing this acceleration is ma. By Newton's third law, this force will have an equal reaction pressing the floor equal to ma. Therefore the total resultant reaction on the floor is mg+ma = m(g+a) which is mg, the weight of the man. So (a) is correct.

A big bed of rock salt with the top portion of the bed containing potash (though not the variety used as ferilizer) has been discovered in Thar Desert at a depth of 100 metres. A massive belt of lead and zinc has been found in the Agucha area, while gold bearing rocks have been discovered in the Tuensang district of Nagaland.

Income easticity of demand measures the responsiveness of demand for any goods to changes in income. With increase in incomes generally the demand for farm products like rice wheat etc, will not change drastically. With income increase, demand for luxuries such as consumer durables etc will increase. The income elasticity  of demand for farm products is thus low.

The first identification of Nipah virus as a cause of an outbreak of encephalitis was reported in 2001 in Meherpur district of Bangladesh. Since, then Outbreaks of the deadly Nipah virus has been recorded almost every year in selected districts of Bangladesh.

Drinking raw date palm sap and contact with a case were identified as the major risk factors for acquiring the disease.