2516: The number of times in a day the Hour-hand and the Minute-hand of a clock at right angles is
(a) 44
(b) 48
(c) 24
(d) 12
2517: Optical fibre works on the principle of
(a) total internal reflection
(b) refraction
(c) scattering
(d) interference
2518: Assertion (A) :
Floods are a recurring feature in the Indo-Gangetic Plain
Reason (R) :
The Indo-Gangetic Plain is built of porous and soft alluvium
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not a correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
2519: 12 constellations referred to as zodiac are:
(a) Imaginary region that encompass the path of the planets.
(b) Signs of Roman gods.
(c) A group of stars.
(d) None of the above
2520: Consider the following Pairs : Hills Region
1. Cardamom Hills : Coromandel Coast
2. Kaimur Hills : Konkan Coast
3. Mahadeo Hills : Central India
4. Mikir Hills : North-East India
Which of the above pairs is/are correctly matched?
(a) 1 and 2
(b) 2 and 3
(c) 3 and 4
(d) 2 and 4