Dear Deepak,

If you are preparing for any government exam General Knowledge comes at the first priority and General knowledge is also divided into two parts:

Static GK

Current Affairs

For Static GK i would suggest that Lucent will be the best as it has a good gist of all the topics asked in many government exams. But for current affairs, the best source will be the newspaper else if are not updated with the newspaper you should follow any yearbook published in the current year. 

Apart from that i would suggest you practice R.S.Agrawal for Quantitative Aptitude.

For English, you can refer to Wren and Martin.

But if you are preparing for UPSC this is not enough you need to focus on each area separately especially for Current Affairs and General Awareness.

I hope this helps. Thank you.