Which of the following factors are responsible for the change in state of solid carbon dioxide when kept exposed to air ?
(i) increase in pressure
(ii) increase in temperature
(iii) decrease in pressure
(iv) decrease in temperature

(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (ii) and (iv)

Arrange the following compounds in the increasing order of their densities.

(a) (i) < (ii) < (iii) <(iv) (b) (i) < (iii) < (iv) < (ii)

(c) (iv) <(iii) <(ii) < (i) (d) (ii) < (iv) < (iii) < (i)

In which of the following molecules carbon atom marked with asterisk (*) is asymmetric?

(a) (i), (ii), (iii) and (iv) (b) (i) ,(ii) and (iii)

(c) (ii), (iii) and (iv) (d) (i), (iii) and (iv)