16: Black hole is:
(a) A magnetic dark cavity
(b) Name of a star
(c) A hole in the moon
(d) A dying star
17: Cobalt-60 is commonly used in radiation therapy because it emits
(a) alpha rays.
(b) beta rays.
(c) gamma rays.
(d) X-rays.
18: In which type of rocks, fossils are more abundantly found?
(a) Igneous
(b) Metamorphic
(c) Sedimentary
(d) None of these
19: Indian National Congress was founded by:
(a) W. C. Bannerjee
(b) A. O. Hume
(c) Mahatma Gandhi
(d) Annie Besant
20: A group of workers promise to complete a piece of work in 10 days, but five of them do not report for work. If it took the remaining workers 12 days to complete the work, then the number of workers originally hired was
(a) 15
(b) 25
(c) 30
(d) 45