Please guide how to tackle this problem in physical chemistry

I sit for almost 1hr 30mins and try solving physical chemistry problems of exercise 1 (subjective) from resonance book and end up doing 3 to 4 problems on an average...
This problem is not with one or two chapters but with almost every chapter which involves of class 12..
I have read the theory multiple times..still facing the problem ..
For I sat for 1hr15min and ended up trying 4 questions out of which I was able to solve only 2..
For analysis of type of questions I have uploaded a pic of the questions which I attempted today...

I attempted question no. 4,5,6and 7 out of which I could solve only 4 and 5
Please tell me how to increase this speed...

No special method as such buddy , practice is the only thing that will help , especially in chapter like electrochemistry.
Don't waste too much time on a single problem, this is applicable not only for physical chem but for other subjects too, view solutions and see their approach, and write it somewhere (or by side of the question) so that you can easily revise the questions .