A student forgot to add the reaction mixture to the round bottomed open flask at `27^(@) C` and put it on the flame After a lapse of time he realized his mistake using a pyrometer he found the temperature of the flask was `477^(@)C` What fraction of air would have been expelled out ? .

Options

A. `5//3`
B. `5//6`
C. `3//5`
D. `6//5`

Answer

C

Explanation

Let initially x moles are present at `27^(0)` C
`P_1 V_1 n_1 RT_1 ` (Initialy) ----- (i)
`P_(2) V_(2) = n_(2) RT_(2)` (finaly) --- (ii) from equation (i) & (ii)
`(T_(1))/(T_(2)) = (n_2)/(n_(1)) [ because V_(1) = V_(2) , P_(1) = P_(2)]`
`(300)/(750) = (n_(2))/(x)`
`therefore` fraction of air which have been expelled out
`= (x - (2)/(5) x) lx = (3)/(5)`