Choose the correct answer from the options A, B, C and D given :

The drying agent used to dry HCl gas is :

A : Conc. H₂SO₄
B : ZnO
C : Al₂O₃
D : CaO

Fill in the blanks with the choices given in the bracket:

When sodium chloride is heated with concentrated sulphuric acid below 200°C, one of the products formed is …………… [sodium hydrogen sulphate / sodium sulphate / chlorine]

State one relevant reason for:
Hydrogen chloride gas fumes in moist air.

Complete the following by selecting the correct option from the choices given.

(i) The indicator which does not change colour on passage of HCl gas is ………….. [methyl orange, moist blue litmus, phenolphthalein].

(ii) The acid which cannot act as an oxidizing agent is …………… [conc. H₂SO₄, conc. HNO₃, conc. HCl]