`underset(Z)overset(M)()A(g)rarr underset(Z-4)overset(M-8)()B(g)+(alpha-` particles `)`
`( alpha-` particles are helium nuclei, so will form helium gas by trapping electrons )
The radioactive disintegration follows first `-` order kinetics Starting with 1 mol of A in a 1- litre closed flask at `27^(@)C` pressure developed after tow half- lives is approximately.

Options

A. 25 atm
B. 12 atm
C. 61.5 atm
D. 40 atm

Answer

3

Explanation

`overset(M)(Z)A(g)rarr overset(M-8)(Z-4)B(g)+(alpha-`particles `)`
`overset(M)(Z)A(g)rarr overset(M-8)(Z-4)B(g)+2(overset(4)(2)He(g))`
`(1-(3)/(4))" "(3)/(4)" "2xx(3)/(4)`
After two half life `(3)/(4)` mole of A decomposes.
Total moles after 2 half life `=((1)/(4)+(3)/(4)+2xx(3)/(4))=2.5` mole
`pV=nRT`
`pxx1=2.5xx0.82xx300`
`p=61.5atm`