s-Block Elements

1

A metal M readily forms its sulphate MSO4 which is water-soluble. It forms its oxide MO which becomes inert on heating. It forms an insoluble hydroxide M(OH)2 which is soluble in NaOH solution. Then M is

  1. Mg
  2. Be
  3. Ba
  4. Ca
2

One mole of magnesium nitride on the reaction with an excess of water gives

  1. one mole of ammonia
  2. two moles of nitric acid
  3. one mole of nitric acid
  4. two moles of ammonia
3

KO2 (potassium super oxide) is used in oxygen cylinders in space and submarines because it

  1. absorbs CO2
  2. eliminates moisture
  3. produces ozone
  4. absorbs CO2 and increases O2 content
4

Several blocks of magnesium are fixed to the bottom of a ship to

  1. prevent puncturing by under ­sea rocks
  2. make the ship lighter
  3. prevent action of water and salt
  4. keep away the sharks
5

The solubilities of carbonates decrease down the magnesium group due to a decrease in

  1. hydration energies of cations
  2. lattice energies of solids
  3. inter-­ionic attraction
  4. entropy of solution formation
6

The substance not likely to contain CaCO3 is

  1. a marble statue
  2. sea shells
  3. dolomite
  4. calcined gypsum
7

Based on lattice energy and other consider cations which one of the following alkali metal chlorides is expected to have the highest melting point?

  1. LiCl
  2. NaCl
  3. KCl
  4. RbCl
8

The ionic mobility of alkali metal ions in aqueous solution is maximum for

  1. Li+
  2. Na+
  3. K+
  4. Rb+
9

Which one of the following alkaline earth metal sulphates has its hydration enthalpy greater than its lattice enthalpy?

  1. BeSO4
  2. CaSO4
  3. SrSO4
  4. BaSO4