Q246. Assertion (A): A piece of copper and a piece of glass are heated to the same temperature. When touched, thereafter, the copper piece appears hotter than the glass piece. Reason (R): The density of copper is more than that of glass. Codes:

Assertion (A): An iron ball floats on mercury but gets immersed in water. Reason (R): The specific gravity of iron is more than that of mercury. Codes:

Assertion (A): With the increase of temperature, the viscosity of glycerine increases. Reason (R): Rise of temperature increases kinetic energy of molecules. Co

Assertion (A): The temperature of a metal wire rises when an electric current is passed through it. Reason (R): Collision of metal atoms with each other release

Assertion (A): To dilute sulphuric acid, acid is added to water and not water to acid. Reason (R): Specific heat of water is quite large.

Assertion (A): A jet aircraft moving at Mach Number equal to 1 travels faster at an altitude of 15 km than while moving at Mach Number equal to 1 near the sea l

Assertion (A): A jet aircraft moving at Mach Number equal to 1 travels faster at an altitude of 15 km than while moving at Mach Number equal to 1 near the sea l

Assertion (A): The boiling point of water decreases as the altitude increases. Reason (R): The atmospheric pressure increases with altitude. Codes: (a) Both A a

Assertion (A): Small glass beads fixed on traffic signals glow brightly when light falls upon them. Reason (R): Light is totally reflected when the angle of inc

Assertion (A): A man standing on a completely frictionless surface can propel himself by whistling. Reason (R): If no external force acts on a system, its momen

Assertion (A): The weight of a body decreases with the increase of altitude on earth. Reason (R): The earth is not a perfect sphere. Codes:

Assertion (A): A stick is dipped in water in a slanting position. If observed sideways, the stick appears short and bent at the surface of water. Reason (R): A

Assertion (A): Sodium metal is stored under kerosene. Reason (R): Metallic sodium melts when exposed to air. (a) Both A and R are true and R is the correct expl

Assertion (A): Large cold storage plants use ammonia as refrigerant while domestic refrigerators use chlorofluoro- carbons. Reason (R): Ammonia can be liquefied

Assertion (A): Coal-based thermal power stations contribute to acid-rain. Reason (R): Oxides of carbon are emitted when coal burns.

Assertion (A): The main constituent of the liquefied petroleum gas is methane. Reason (R): Methane can be used directly for burning in homes and factories where

Assertion (A): Cellulose is used in making shatter-proof glass. Reason (R): Polysaccharides are not soluble in water. Codes:

Consider the following statements: 1. Steam at 100°C and boiling water at 100°C contain the same amount of heat. 2. Latent heat of fusion of ice is eq

A hollow sphere of radius R, a hollow cube of side R and a thin circular plate of radius R, made up of the same material, are all heated to 20°C above

When water is heated from 0°C to 10°C. Its volume:

Cloudy nights are warmer compared to clear cloudless nights, because clouds:

Strips of two metals A and B are firmly joined together as shown in the figure. On heating, A expands more than B does. If this jointed strip is heat

Low temperatures (cryogenics) find application in:

"Membrane Bioreactors" are often discussed in the context of:

Which one of the following is synthesised in the human body that dilates blood vessels and increases blood flow?