A reaction in equilibrium is represent by the following equation2A(s)  +  3B(g)  ⇌  3C(g)  + D(g)  +  O2(g)    if the pressure on the system is reduced to half of its original value

(2)2A(s)  +  3B(g)  ⇌  3C(g)  + D(g)  +  O2(g)   If pressure on the system is reduced to half its original value, then equilibrium will shift in forward direction to increase the number of moles of gas to compensate reduction of pressure.∴   Amounts of C and D will increase.