1. When heated from 0 to 100oC volume of a given mass of water will :
a) Increase gradually
b) Decrease gradually
c) Increase and then will decrease
d) Decrease and then will increase
Explanation: From water at 0°C to water at 4°C, on addition of heat, the water surprisingly, contracts till it reaches maximum density at 4°C. This negative thermal expansion is termed as the anomalous expansion of water. From water at 4°C to water at 100°C, water shows a positive cubical thermal expansion like other substances and gradually expand with the increase in temperature.
2. When a bottle of perfume is opened in one corner of a room the smell spreads soon throughout the room. This is an example of
a) Surface tension
b) Capillarity
c) Viscosity
d) Diffusion
Explanation: When a bottle of perfume is opened in a corner of a room, the scent soon spreads all over the room. This physical procedure is called diffusion, due to which the liquid or gaseous molecules travels from the area of higher density to that of the lower density of that substance.
3. Which of the following laws validates the statement that matter can neither be created nor destroyed ?
a) Law of conservation of energy
b) Le Chatelier's Principle
c) Law of conservation of mass
d) Law of osmosis
Explanation: Law of conservation of mass validates the statement that matter can neither be created nor destroyed.
4. The boiling point of liquids vary as
a) Pressure varies
b) Temperature varies
c) Volume varies
d) Density varies
Explanation: The boiling point of a liquid varies according to the applied pressure; the normal boiling point is the temperature at which the vapour pressure is equal to the standard sea-level atmospheric pressure (760 mm [29.92 inches] of mercury). At sea level, water boils at 100°C (212°F).
5.The freezing point of fresh water is ________ .
a) 4°C
b) 3°C
c) 5°C
d) 0°C
Explanation: Freezing point is the temperature where a liquid converts into solid. Water converts into ice at zero degrees centigrade. So degree zero centigrade is the freezing point of water.
6. Friction can be reduced by changing from
a) Static to Dynamic
b) Rolling to Sliding
c) Dynamic to Static
d) Sliding to Rolling
Explanation: Friction can be reduced by changing from sliding to rolling. Replace sliding friction with rolling element friction, such as with the use of rolling element bearings.
7. It is more difficult to walk on ice than on a concrete road because
a) There is very little friction between the ice and feet pressing it
b) Ice is soft when compared to concrete
c) There is more friction between the ice and feer
d) None of these
Explanation: Main thing is that we find more friction on roads than on ice. As, we can call the friction as grip on roads. We can hear the word by tyre companies as the road grip tyres. Here the grip of the tyre is more than that of any normal tyre.
8. A ball rolling along the ground gradually slows down and finally comes to rest is due to ________
a) Friction
b) Magnetic force
c) Electrostatic force
d) Muscular force
Explanation: A ball rolling along the ground gradually slows down and finally comes to rest. It is the force of friction between the surface of the ball and the ground that brings the moving ball to rest.
9. Frictional force acts in
a) The same direction as the motion
b) The opposite direction of the motion
c) All the directions
d) Upward direction
Explanation: The part which is tangent to the contacting surfaces is called the frictional force. Friction is a resisting force that acts on a body to prevent or retard its motion. Friction force always acts tangent to the surface at points of contact. Friction force acts opposite to the direction of motion.
10. The force which makes a vehicle to stop when break is applied is called
a) Gravitational force
b) Vanderwalls force
c) Frictional force
d) Covalant force
Explanation: A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction.