(a) Complete the following chemical equations:
(i) Cu + HNO₃(dilute) \(\rightarrow\)
(ii) XeF₄ + O₂F₂ \(\rightarrow\)
(b) Explain the following observations:
(i) Phosphorus has greater tendency for catenation than nitrogen.
(ii) Oxygen is a gas but sulphur a solid.
(iii) The halogens are coloured.  Why?

(a) Draw the structures of the following molecules:
(i) (HPO₃)₃
(ii) BrF₃
(b) Complete the following chemical equations:
(i) HgCl₂ + PH₃ \(\rightarrow\)
(ii) SO₃ + H₂SO₄ \(\rightarrow\)
(iii) XeF₄ + H₂O \(\rightarrow\)

(a) Draw the structures of the following:
(i) N₂O₅
(ii) XeOF₄
(b) Explain the following observations:
(i) The electron gain enthalpy of sulphur atom has a greater negative value than that of oxygen atom.
(ii) Nitrogen does not form pentahalides.
(iii) In aqueous solutions, HI is a stronger acid than HCl.

(a) Draw the structures of the following:
(i) XeF₄     (ii) H₂S₂O₇
(b) Explain the following observations:
(i) Phosphorus has a greater tendency for catenation than nitrogen.
(ii) The negative value of electron gain enthalpy is less for fluorine than that for chlorine.
(iii) Hydrogen fluoride has a much higher boiling point than hydrogen chloride.

(a) Complete the following chemical equations:
(i) F₂ + H₂O         \(\to\) .............
(ii) Ca₃P₂ + H₂O   \(\to\) .............
(iii) XeF₄ + H₂O    \(\to\) .............
(b) Draw structures of the following species:
(i) H₂S₂O₇ (ii) NO₃^-

(a) Describe the favourable conditions for the manufacture of
(i) ammonia by Haber's process, and
(ii) sulphuric acid by Contact process.
(b) Draw the structures of the following:
(i) PCl₅ (g)
(ii) S₈ (g)
(iii) ClF₃ (g)

Elemental phosphorous does not exist as \(P_{ 2 }\) like  \(N_{ 2 }\) .Why?

(a) Elements of Gr. 16 generally show lower value of first ionization enthalpy compared to the corresponding periods of Gr. 15.Why ?
(b) What happens when:
(i) Concentrated H₂SO₄ is added to CaF₂?
(ii) Sulphur dioxide reacts with chlorine in the presence of charcoal?
(iii)Ammonium chloride is treated with Ca(OH)₂?

On heating compound (A) gives a gas (B) which is a constituent of air.  This gas when treated with 3 mol of hydrogen (H₂) in the presence of a catalyst gives another gas (C) Which is basic in nature.  Gas C on further oxidation in moist condition gives a compound (D) which is a part of acid rain.  Identify compound (A) to (D) and also give necessary equations of all the steps involved.