Physics

1. Metals are good conductors of electricity because
Ans. they contain free electrons

2. Siphon will fail to work if
Ans. the level of the liquid in the two vessels are at the same height

3. Magnetism at the center of a bar magnet is
Ans. Zero

4. Isotopes of an element contain
Ans. the same number of protons but different number of neutrons

5. Rainbow is due to
Ans. refraction and reflection of sunlight by water droplets

6. Which of the following shows the masses of the three elementary particles in decreasing order ?
Ans. Baryons , Mesons , Leptons

7. Intensity of sound at a point is ___________its distance from the source ?
Ans. Inversely proportional to square of

8. It is more difficult to walk on a sandy road than on a concrete road because
Ans. the friction between sand and feet is less than that between concrete and feet

9. What is the effect of the decrease in pressure with the increse in speed of the fluid in a horizontal pipe called ?
Ans. Venturi's effect

10. Supersonic plane fly with the speed
Ans. greater than the speed of sound