A stream of air was successively passed through three tubes X, Y and Z containing a concentrated aqueous solution of KOH, red hot copper powder and fused calcium chloride respectively. What was the composition of the gas emanating from tube Z?

• A.CO₂ ad ithe inert gases
• B.N₂, CO₂ and the inert gases
• C.N₂ and the inert gases
• D.water vapour, N₂ and the inert gases
• E.