Physical Properties of Matter

1. A form of matter has no fixed shape but it has a fixed volume.An example of this form of matter is : [68th B.P.S.C (pre) 2022]

Correct Answer: (c) kerosine

Solution:Among the given option kerosene is liquid which has no fixed shape but it has a fixed volume carbon steel is a solid and has a definite shape and volume.While krypton is a gas which has neither a definite shape nor volume.

2. With reference to the mechanical properties of solids, which of the following statement/s is/are correct? [U.P.R.O./A.R.O.(pre)]

(1) The Young's Modulus of rubber is greater than that of steel.
(2) The stretching of a coil is determined by its Shear Modulus.

(a) only 1
(b) only 2
(c) both 1 and 2
(d) neither 1 and 2

Correct Answer: (b) only 2

Solution:The Young's modulus (E), also known as modulus of elasticity, is a property of the material that tells us how easily it can stretch and deform and is defined as the ratio of tensile stress to tensile strain. Where stress is the amount of force applied per unit area and strain is extension per unit length. The Young's modulus for steel is much more than that for rubber. For same longitudinal strain, steel will have greater tensile stress than that of rubber. Thus, statement (1) is incorrect.
The shear modulus, also known as the modulus of rigidity, is a material property that measures the stiffness of a solid material in response to shear stress. It describes a material's ability to resist deformation when subjected to forces acting parallel or tangentially to its surface. It is the measure of the rigidity of the body, given by the ratio of shear stress to shear strain. The stretching of a coil changes its shape. Hence, it is determined by its shear modulus. Thus, statement (2) is correct.

3. Spherical form of a drop is due to - [Chhattisgarh P.C.S.(PRE) 2003, 67th B.P.S.C. (PRE) 1994, Uttarakhand P.C.S.(mains) 2002]

(a) density of liquid
(b) surface tension
(c) atmosphere pressure
(d) gravitational force

Correct Answer: (b) surface tension

Solution:The shape of drop of rain is constrained by the surface tension which tries to give it the shape for which the surface area is minimum for the given volume.The spherical shape has the minimum surface area .That's why rain drops acquire spherical shape.

4. A drop of water is spherical in shape this is due to : [Uttarakhand Lower Sub.(PRE) 2010]

(a) surface tension
(b) low temperature
(c) air resistance
(d) viscosity of water

Correct Answer: (a) surface tension

Solution:The shape of drop of rain is constrained by the surface tension which tries to give it the shape for which the surface area is minimum for the given volume.The spherical shape has the minimum surface area .That's why rain drops acquire spherical shape.

5. The rain drop of water are spherical because - [U.P.P.C.S.(pre) 2005]

(a) They fall from big height
(b) The air has resistance
(c) The water has the surface tension
(d) None of the above

Correct Answer: (c) The water has the surface tension

Solution:The shape of drop of rain is constrained by the surface tension which tries to give it the shape for which the surface area is minimum for the given volume.The spherical shape has the minimum surface area .That's why rain drops acquire spherical shape.

6. The tendency of a liquid drop to contract and occupy minimum area is due to : [U.P.P.C.S.(pre) 2005]

(a) surface tension
(b) viscosity
(c) density
(d) vapour pressure

Correct Answer: (a) surface tension

Solution:The shape of drop of rain is constrained by the surface tension which tries to give it the shape for which the surface area is minimum for the given volume.The spherical shape has the minimum surface area .That's why rain drops acquire spherical shape.

7. Oil spreads on water surface because - [U.P.P.S.C.(GIC) 2010, U.P.P.C.S.(PRE) 1994]

(a) oil is less dense than water
(b) oil is denser than water
(c) surface tension of oil is more than water
(d)surface tension of oil is less than water

Correct Answer: (d)surface tension of oil is less than water

Solution:Oil spread on water surface because the surface tension of oil is less than the water.therefore when the oil is poured over water the greater value of surface tension of water pulls oil in all direction and as such it spreads on the water.

8. Kerosene oil floats on water because - [Uttarakhand Lower Sub.(PRE) 2010]

(a) its density is greater than the density of water
(b) its density is less than the density of water
(c) its density is equal to that of the density of water
(d) none of the above

Correct Answer: (b) its density is less than the density of water

Solution:Kerosene oil floats on water because its density is less than the density of water.

9. Pressure inside the soap bubble is - [U.P.P.C.S.(MAINS) 2014, 1995]

(a) more than atmosphere pressure
(b) less than the atmosphere pressure
(c) equal to the atmosphere pressure
(d) half of the atmospheric pressure

Correct Answer: (a) more than atmosphere pressure

Solution:Soap bubbles are large because when soap dissolved in water its surface tension is reduced.The pressure inside a soap is more than atmospheric pressure.

10. If two bubbles of soap of diameter come in contact with a tube then what will happen ? [R.A.S./R.T.S (PRE) 2007]

(a) the size of the both bubble remains the same
(b) the smaller bubble become smaller and bigger bubble become bigger
(c) the smaller bubble will become larger and larger bubble will become smaller to get the same size
(d) both the bubbles will burst as soon as they come in contact

Correct Answer: (b) the smaller bubble become smaller and bigger bubble become bigger

Solution:The excess pressure inside the soap bubble is inversely proportional to the radius of the soap bubble p∝1/r when these two bubble are connected by a tube the air will flow from the smaller bubble to bigger bubble due to the fact that smaller having smaller radius will exert more pressure .hence the bigger bubble would grow at the expense fo the smaller one.

Physical Properties of Matter