NCERT Exemplar Class 11 Chemistry Chapter 5 MCQ

(b) Surface TensionExplanation:Raindrops take up the spherical shape due to the surface tension of water which is caused due to the tendency of water molecules to stick together. The spherical shape is having the least possible surface area due to which it can resist any of the external force in the atmosphere.

(b) Grahams LawExplanation:Grahams law states that the rate of diffusion of a gas is inversely proportional to the square root of its molecular weight. In the same conditions of temperature and pressure, the molar mass is proportional to the mass density. Therefore the rate of diffusion of different gases is inversely proportional to the square root of their mass densities.r α (\(\sqrt{\frac {1}{d}}\))and r α (\(\sqrt{\frac {1}{M}}\))

(a) Boyles lawExplanation:In 1662 Robert Boyle studied the relationship between volume and pressure of a gas of fixed amount at constant temperature. He observed that volume of a given mass of a gas is inversely proportional to its pressure at a constant temperature. Boyles law, published in 1662, states that, at constant temperature, the product of the pressure and volume of a given mass of an ideal gas in a closed system is always constant. It can be verified experimentally using a pressure gauge and a variable volume container. It can also be derived from the kinetic theory of gases: if a container, with a fixed number of molecules inside, is reduced in volume, more molecules will strike a given area of the sides of the container per unit time, causing a greater pressure.A statement of Boyles law is as follows:The volume of a given mass of a gas is inversely related to pressure when the temperature is constant.​V ∝ (\(\frac {1}{P}\)) meaning “Volume is inversely proportional to Pressure”, orP ∝ (\(\frac {1}{V}\)) meaning “Pressure is inversely proportional to Volume”, orwhere P is the pressure, and V is the volume of a gas, and k1 is the constant in this equation.

(a) 2 : 1Explanation:According to Grahams law$(\(\frac {r_1}{r_2}\)$) = $(\(\sqrt{\frac {M_1}{M_2}}\)$)$(rHe/rCH4)$ = (\(\sqrt{\frac {16}{4}}\))= (\(\frac {1}{2}\))

(a) The particles move faster.Explanation:There is a great deal of empty space between particles, which have a lot of kinetic energy. The particles move very fast and collide into one another when the gas is heated up, causing them to diffuse, or spread out, until they are evenly distributed throughout the volume of the container.