40. (i) Chlorine is prepared in the laboratory by the .............. (state the type of reaction) of ............... hydrochloric acid.   41. (ii) Chlorine is a ............... (state the colour) gas which is .............. than air.   42. (iii) Bleaching powder (CaOCl2) smells like chlorine due to the action of carbon dioxide on it. Write the equation for the reaction.   43. (iv) Write the balanced equation for the action of chlorine with excess of ammonia.