p-Block Elements (Group 15–18)

Among the following the correct order of acidity is

1. HClO2 < HClO < HClO3 < HClO4
2. HClO4 < HClO2 < HClO < HClO3
3. HClO3 < HClO4 < HClO2 < HClO
4. HClO < HClO2 < HClO3 < HClO4

Hot concentrated sulphuric acid is a moderately strong oxidizing agent. Which of the following reactions does not show oxidizing behaviour?

1. Cu + 2H2SO4 CuSO4 + SO2 + 2H2O
2. 3S + 2H2SO4 3SO2 + 2H2O
3. C + 2H2SO4 CO2 + 2SO2 + 2H2O
4. CaF2 + H2SO4 CaSO4 + 2HF

Strong reducing behavior of H3PO2 is due to

1. high electron gain enthalpy of phosphorus
2. high oxidation state of phosphorus
3. presence of two -OH groups and one P-H bond
4. presence of one -OH group and two P-H bonds.

The variation of the boiling points of the hydrogen halides is in the order HF > HI > HBr > HCl. What explains the higher boiling point of hydrogen fluoride?

1. There is strong hydrogen bonding between HF molecules.
2. The bond energy of HF molecules is greater than in other hydrogen halides.
3. The effect of nuclear shielding is much reduced in fluorine which polarises the HF molecule.
4. The electronegativity of fluorine is much higher than for other elements in the group.

Which of the statements given below is incorrect?

1. O3 molecule is bent.
2. ONF is isoelectronic with O2N-
3. OF2 is an oxide of fluorine.
4. Cl2O7 is an anhydride of perchloric acid.

Nitrogen dioxide and sulphur dioxide have some properties in common. Which property is shown by one of these compounds, but not by the other?

1. Is soluble in water.
2. Is used as a food preservative.
3. Forms 'acid-rain'.
4. Is a reducing agent.

Acidity of diprotic acids in aqueous solutions increases in the order

1. H2S < H2Se < H2Te
2. H2Se < H2S < H2Te
3. H2Te < H2S < H2Se
4. H2Se < H2Te < H2S

Which is the strongest acid in the following?

1. HClO4
2. H2SO3
3. H2SO4
4. HClO3

Roasting of sulphides gives the gas X as a byproduct. This is a colourless gas with choking smell of burnt sulphur and causes great damage to respiratory organs as a result of acid rain. Its aqueous solution is acidic, acts as a reducing agent and its acid has never been isolated. The gas X is

1. CO2
2. SO3
3. H2S
4. SO2

Identify the incorrect statement, regarding the molecule XeO4:

1. XeO4 molecule is square planar.
2. There are four p -d bonds.
3. There are four sp3-p, bonds.
4. XeO4 molecule is tetrahedral.