CBSE
Multiple Choice QuestionsAssertion: Machine parts are jammed in winter.
Reason: The viscosity of lubricant used in machine parts increase at low temperatures.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Work of 3.0 × 10-4 joule is required to be done in increasing the size of a soap film from 10 cm × 6 cm to 10 cm × 11 cm. The surface tension of the film is
5 × 10-2 N/m
3 × 10-2 N/m
1.5 × 10-2 N/m
1.2 × 10-2 N/m
In old age arteries carrying blood in the human body become narrow resulting in an increase in the blood pressure. This follows from
Pascal's law
Stoke's law
Bernoulli's principle
Archimede's principle
If the water falls from a dam into a turbine wheel 19.6 n below, then the velocity of water ar turbines is ( Take g = 9.8 m/s )
9.8 m/s
19.6 m/s
39.2 m/s
98.6 m/s
A capillary tube of radius r is immersed in water and water rises in it to a height h. The mass of water in the capillary tube is 5 g. Another capillary tube of radius 2 r is immersed in water. The mass of water that will rise in this tube is
2.5 g
5.0 g
10 g
20 g
Which of the following physical quantities do not have same dimensions?
pressure and stress
tension and surface tension
strain and angle
energy and work
Assertion: Liquid molecules have greater potential energy at the melting point.
Reason: Intermolecular spacing between molecules increases at melting point.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
A liquid is kept in a cylindrical vessel which is being rotated about a vertical axis through the centre of the circular base. If the radius of the vessel is r and angular velocity of rotation is w, then the difference in the heights of the liquid at the centre of the vessel and the edge is
Assertion: A needle placed carefully on the surface of water may float, whereas a ball of the same material will always sink.
Result: The buoyancy of an object depends both on the material and shape of the object.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Neglecting the density of air, the thermal velocity obtained by a raindrop of radius 0.3 nm falling through air of viscosity 1.8 × 105 N s m2 will be
10.9 m s-1
7.48 m s-1
3.7 m s-1
12.8 m s-1
