Q324. Given below: Assertion (A): In the periodic table of chemical elements, electron affinity is always found to increase from top to bottom in a group Reason (R): In a group, the atomic radii generally increase from top to bottom.

Assertion(A): Synthetic detergents can lather well in hard water. Reason (R): Synthetic detergents form soluble calcium and magnesium salts with hard water.

Consider the following statements with reference to the periodic table of chemical elements: 1. Ionisation potential gradually decreases along a period. 2. In a

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

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): 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): 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): Unsaturated fats are more reactive compared with the saturated fats. Reason (R): Unsaturated fats have only single bonds in their structure.

Assertion (A): Formic acid is a stronger acid than acetic acid. Reason (R): Formic acid is an organic acid. (a) Both A and R are true and R is the correct expla

Assertion (A): Phenyl is used as a household germicide. Reason (R): Phenyl is phenol derivative and phenol is an effective germicide. (a) Both A and R are true

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): Amoeba reproduces by fission. Reason (R): All unicellular organisms reproduce by asexual methods.

Assertion (A): Radio waves bend in a magnetic field. Reason (R): Radio waves are electromagnetic in nature.

Assertion (A): Radio waves bend in a magnetic field. Reason (R): Radio waves are electromagnetic in nature.

Consider the following statements: 1. Baking soda is used in fire extinguishers. 2. Quick lime is used in the manufacture of glass. 3. Gypsum is used

Salts of which of the following elements provide colours to fireworks?

Which one of the following statements is NOT correct?

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

Match List-I (Oxidation number) with List II (The element) and select the correct answer using the codes given below the lists: | List-I (Oxidation n

An aqueous solution of copper sulphate is acidic in nature because the salt undergoes:

Match List-I with List-II and select the correct answer using the codes given below the lists: | List-I | List-II | | :--- | :--- | | A. German silve

Which one of the following materials is very hard and very ductile?