Questions

A solid sinks in a liquid if its density is greater than that of the liquid. if less, it floats

In a chemical reaction, substances (elements or compounds) called reactants are changed into other substances (compounds or elements) called products. Hence, reactants are those which start the chemical reaction.

For example:

1. In the burning of natural gas, methane (CH4) and oxygen (O2) are the reactants in the chemical reaction. are the substances formed by a chemical reaction. In the burning of natural gas, carbon dioxide (CO2) and water (H2O) are the products formed by the reaction.

2. H2+O2 ----> H2O

Here H2 & O2 are called Reactants and H2O is called Product.

To evaporate the water that oozes out, heat is required. Part of this heat is taken from the water inside which therefore become cool. Therefore (C) is correct. Here evaporation is less, so cooling too is less.

Number of spectral lines from a state n to ground state is

                   n(n-1)/2 = 6

Darjeeling is in West Bengal and other two are in Himachal Pradesh.