771: Cryogenic engines find applications in
(a) sub-marine propulsion
(b) frost-free refrigerators
(c) rocket technology
(d) researches in superconductivity
772: Colour blindness is:
(a) More common among women
(b) Very rare in women
(c) Very rare in men
(d) Found to the same extent in both the sexes
773: In an objective test there are 60 questions. Each question carries four alternative answers only one of which is correct. Suppose A and B are two candidates both of whom know correct answers to 30 questions. A answers only 30 questions while B answers all 60 questions choosing answers at random for those he does not know the answers of. If each question carries a mark of 1 and no negative marks are awarded, the marks obtained by B are expected to be larger than those obtained by A by
(a) 0
(b) 15
(c) 5
(d) 7.5
774: Groups each containing 3 boys are to be formed out of 5 boys-A,B,C,D and E such that no one group contains both C and D together. What is the maximum number of such different groups ?
(A) 8
(B) 7
(C) 5
(D) 6
775: 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