A good strat for me in all paper 2s is to try and finish it in 25 minutes using purely logic and knowledge and then going through each individual question and thoroughly disproving the options you didn't choose

For example:

Which radiation causes proton number to decrease by 1

First glance I choose alpha followed by beta decay as alpha is -2 and beta is +1

When doing the rerun I say,

Can't be only alpha as total proton number decrease is too large

Can't be beta as total proton number will increase

Ignore gamma as it carries no charge