AIEEE 2006 Solved Paper

Since the reaction is 2 nd order w.r.t CO. Thus, rate law is given as.
r=k[CO]2
Let initial concentration of CO is a i.e. [CO]=a
∴‌‌r1=k(a)2=ka2
when concentration becomes doubled, i.e. [CO]=2a
‌∴‌‌r2=k(2a)2=4ka2
‌∴‌‌r2=4r1
So, the rate of reaction becomes 4 times.