KO₂ is used in oxygen cylinder in space air craft and submarines because it:

(a) absorbs CO₂ and increase O₂ content

(b) eliminate moisture

(c) absorbs CO₂

(d) produces O₂

Manufacture of NaOH is done by:

(1) Castner - Kellner process

(2) Solvay process

(3) Brine process

(4) Mond's process

Lithium is the only alkali metal which is not placed in kerosene but is wrapped in paraffin wax, because:

(1) it reacts with kerosene

(2) it floats to the surface of kerosene because of low density

(3) it does not react with air and H₂O

(4) none of the above

When CO₂ is bubbled into an aqueous solution of Na₂CO₃, the following is formed:

(1) H₂O

(2) OH-

(3) NaHCO₃

(4) NaOH

Which of the following acts as reducing agent as well as oxidising agent?

(1) Na₂O

(2) Na₂O₂

(3) NaNO₃

(4) KNO₃

Which of the following alkali metal ion in aqueous solution is the best conductor of electricity?

(1) Li⁺

(2) Na⁺

(3) Cs⁺

(4) K⁺

Which of the following is soluble in pyridine:-

(1) LiCl

(2) CsCl

(3) NaCl

(4) KCl

Ionic mobility of which of the following alkali metal ions is lowest when an aqueous solution of their salts are put under an electric field?

(1) Na                       

(2) K

(3) Rb                       

(4) Li

The solubility of metal halides depends on their nature, lattice enthalpy and hydration enthalpy of the individual ions. Amongst fluorides of alkali metals, the lowest solubility of LiF in water is due to:

(a) Ionic nature of lithium fluoride             

(b) High lattice enthalpy

(c) High hydration enthalpy of lithium ion

(d) Low ionisation enthalpy of lithium atom

By adding gypsum to cement:

(1) Setting time of cement becomes less       

(2) Setting time of cement increases

(3) Colour of cement becomes light               

(4) Shining surface is obtained