10cm3 of CO is mixed and sparked with 100cm3 of air containing 21% O2. If all the volumes measured at S.T.P. the volume of resulting gases would be?

A.

90cm3

B.

100cm3

C.

105cm3

D.

110cm3

E.

115cm3

Correct answer is C

2CO(g) + O2(g) ---> 2CO\(_2\)(g)
2vol 1vol 2vol
Volume in cm\(^3\) Before sparking: 10 // 21
Volume in cm\(^3\) On sparking 10 // 5 // 10
Volume in cm\(^3\) After sparking: 0// 16 // 10
Total volume of resulting gas = Volume of [excess oxygen + CO\(_2\) produced + unreactive components]
= 16 + 10 + 79   → 105cm\(^3\)