(a) Draw the structures of the following molecules:

(i) (HPO₃)₃

(ii) BrF₃

(b) Complete the following chemical equations:

(i) HgCl₂ + PH₃-->

(ii) SO₃ + H₂SO₄ -->

(iii) XeF₄ + H₂O  -->

 OR

(a) What happens when?

(i) Chlorine gas is passed through a hot concentrated solution of NaOH?

(ii) Sulphur dioxide gas is passed through an aqueous solution of a Fe (III) salt?

(b) Answer the following:

(i) What is the basicity of H₃PO₃ and why?

(ii) Why does fluorine not play the role of a central atom in inter-halogen compounds?

(iii) Why do noble gases have very low boiling points?

(i) (HPO₃)₃

(ii) BrF₃ has a bent T-shape and can be drawn as follows.

(b)

(i) 3 HgCl₂ + 2 PH₃ --> Hg₃P₂ + 6 HCl

(ii) SO₃ + H₂SO₄ ---> H₂S₂O₇

(iii) 6 XeF₄ +12 H₂O ---> 4Xe + 2 XeO₃ + 24 HF + 3O₂
Or
(a)

(i) When chlorine is passed through a hot concentrated solution of NaOH, it undergoes disproportionation in which chlorine is simultaneously reduced to Cl^-and is oxidised to

3Cl₂ + 3NaOH --> 5NaCl + NaClO₃ + 3H₂O

(ii) SO₂ acts as a reducing agent when passed through an aqueous solution containing Fe(III) salt. It reduces Fe(III) to Fe(II) i.e., ferric ions to ferrous ions.

2Fe³⁺ + SO₂ + 2H₂O ---> 2Fe²⁺ + SO₄^2-+ 4H⁺

(b)

(i) Basicity of H₃PO₃ depends upon the number of ionizable -OH groups present in the molecule. That is the number of hydrogen attached to the electronegative atom oxygen.

H₃PO₃ has two ionizable –OH group, thus its basicity is 2

The structure of H₃PO₃ follows as:

(ii) Fluorine does not play the role of a central atom in inter-halogen compounds because of the absence of d- orbital. Also, because of the small size of fluorine, it cannot accommodate larger halogen groups.

(iii) The noble gases have low boiling point due to the fact that the noble gases are mono atomic. Having no interatomic forces except weak dispersion forces.