551: Two taps can fill a tank separately in 20 minutes and 30 minutes respectively. If both the taps are opened simultaneously, then the tank can be filled in:

(a) 50 minutes

(b) 15 minutes

(c) 12 minutes

(d) 10 minutes
552: Which of the following is/are the example /examples of chemical change ?

1. Crystallization of sodium chloride.
2. Melting of ice
3. Sourcing of milk

Select the correct answer using the code given below:

(a) 1 and 2 only
(b) 3 only
(c) 1, 2 and 3
(d) None
553: The best conceiving season for cows and buffaloes is:

(a) Summer

(b) Winter

(c) Spring

(d) There is no definite relationship between conceiving and season
554: Which one of the following areas of India produces largest amount of cotton ?
(a) North-western India and Gangetic West Bengal
(b) North-western and Western India
(c) Western and Southern India
(d) Plains of Northern India
555: The national motto of India, Satyameva Jayate inscribed below the Emblem of India is taken from

(a) Katha Upanishad
(b) Chandogya Upanishad
(c) Aitareya Upanishad
(d) Mundaka Upanishad