Which is lighter than dry air?

(a) Moist air                              (b) SO₂

(c) Cl₂                                      (d) O₂

Which gas when passed through dilute blood will impart a cherry red colour to the solution?

(a) CO₂                               (b) COCl₂

(c) NH₃                               (d) CO

The condition of SATP refers for:

(a) 25 $°$C and 2 atm             (b) 25 $°$C  and 1 atm

(c) 0 $°$C  and 2 atm              (d) 25 $°$C  and 1 bar

Which of the following contains the greatest number of nitrogen atoms ?

(A) 500 ml of 2.0 $\mathrm{M} {\mathrm{NH}}_3$

(B) One mole of ${\mathrm{NH}}_4\mathrm{Cl}$

(C) $6.02 \times {10}^{23}$ molecules of ${\mathrm{NO}}_2$ gas

(D) 22.4 litres of ${\mathrm{N}}_2$ gas at 0ºC and 1 atm.