The density of water is greatest at:

(A) -32°C
(B) 0°C
(C) 4°C
(D) 100°C

Q. As the temperature rises gradually, it’s surface tension:
(A) goes on increasing
(B) goes on decreasing
(C) remains unchanged
(D) increase only when the heat is too intense

Q. When a beam of light passes from air into water, its speed:
(A) increases
(B) decreases
(C) remains the same
(D) None of these

Answers:
1. (C) 4°C
2. (B) goes on decreasing
3. (B) decreases