4221: The age of a father is twice that of the elder son. Ten years hence the age of the father will be three times that of the younger son. If the difference of ages of the two sons is 15 years, the age of the father is
(a) 100 years
(b) 70 years
(c) 60 years
(d) 50 years
4222: Which one of the following is also called Stranger Gas?
(a) Argon
(b) Nitrous oxide
(c) Xenon
(d) Neon
4223: Examine the following statements:
I. Either A and B are of the same age or A is older then B.
II. Either C and D are of the same age or D is older than C.
III. B is older than C.
Which one of the following conclusions can be drawn from the above statements?
(a) A is older than B
(b) B and D are of the same age
(c) D is older than C
(d) A is older than C
4224: What is the correct sequence of the rivers Godavari, Mahanadi, Narmada and Tapi in the descending order of their lengths?
(a) Godavari--Mahanadi--Narmada--Tapi
(b) Godavari--Narmada--Mahanadi--Tapi
(c) Narmada--Godavari--Tapi--Mahanadi
(d) Narmada--Tapi--Godavari--Mahandai
4225: The sun derives its energy from:
(a) Nuclear fission reactions.
(b) Nuclear fusion reactions.
(c) Oxidation of helium.
(d) Fission of noble metals.