GK Syllabus is kind of infinite so there is noa ny particular book for this. The exams of SNAP & IIFT has different type of GK questions. Here are some preparation tips you can prefer.

Read News paper daily

Go with current affairs & Magzines

Make notes on current Events

SNAP Key areas

National Affairs including social, sports, Films, awards, Science etc.

International Affairs including personalities in News, Major Events etc.

Economy and Finance based current affairs like various Schemes, Budget, Survey etc.

GK in IIFT is based on both Current Affairs & Static GK. You can prepare the topic on-

Polity

Business Affairs

International Affairs

National Affairs

Sports

Good Luck!