Question

Match the compounds/metal in X with their use in Y. Hence correct order is:

i. A-I,B-III,C-II,D-IV
ii. A-III,B-IV,C-II,D-I
iii. A-II,B-I,C-III,D-IV
iv. A-IV,B-II,C-III,D-I

Answer 1

Earlier water was used as a coolant in the reactors now for high pressure reactor molten metals are used. Alkali metals are used as soap in the form of hydroxides. Superoxides occur as a source for oxygen.

Complete answer:
The boiling point of water is much lower than that of molten metals. For very high power nuclear reactors instead of pressurised water we use molten metal for deep cooling. Various metals are used in the nuclear reactors. The metal coolants are more effective in removing heat more rapidly. Sodium in liquid form is widely used as a coolant because it does not corrode steel and other alloys that are used in reactors. Hence, option A matches with III.
Potassium is widely used in the formation of soap. Both potassium and sodium are suitable for soap formation but the soaps of potassium are more soluble than that of the sodium salt. Potassium soaps are known as soft soaps when present in concentrated forms. Option B matches with IV.
Potassium nitrate is used in gunpowder. This creates an explosion under fire or pressure conditions. When we heat potassium nitrate it forms potassium nitrite and oxygen. Option C matches with II.
As the amount of oxygen is less under water. The use of superoxide of potassium occurs as a source of oxygen as chemical oxygen generators. Option D matches with I.
Hence, the correct option is B.

Note: Potassium nitrate is also used as a rocket fuel. Potassium nitrate is an ionic salt and occurs naturally as a mineral. The other uses include its use in fertilizers and fireworks.