Which one of the following has greater active mass

Options

A. 200 gm of lime stone in 2 lit vessel
B. 90 gm of `CS_2` liquid in 100 ml vessel
C. 56 gm of `N_2` gas in 0.5 lit vessel
D. 1 mole of `O_2` gas at STP

Answer

C

Explanation

Active mass of pure solids and liquids = 1
gases = `(n)/(V_("(lit)"))`