Additional Questions - Chapter 7 Properties of Matter 11th Science Guide Samacheer Kalvi Solutions - SaraNextGen [2024-2025]

Updated On May 15, 2024

By SaraNextGen

Additional Questions
I. Choose the correct answer from the following:
Question 1.
The force required to stretch a steel wire $1 \mathrm{~cm}^2$ in cross section to double its length is (given $Y=2 \times$ $\left.10^{11} \mathrm{Nm}^{-2}\right)$
(a) $10^7 \mathrm{~N}$
(b) $2 \times 10^7 \mathrm{~N}$
(c) $10^{11} \mathrm{~N}$
(d) $2 \times 10^{11} \mathrm{~N}$
Answer:
(b) $2 \times 10^7 \mathrm{~N}$
$
\begin{aligned}
& \mathrm{F}=\frac{\mathrm{YA} \Delta l}{l}, \text { Here } \Delta l=l \Rightarrow \mathrm{F}=\mathrm{YA} \\
& \mathrm{F}=2 \times 10^{11} \times 10^{-4}=2 \times 10^7 \mathrm{~N}
\end{aligned}
$
Question 2.
The fractional change in volume per unit increase in pressure is called
(a) Pressure co-efficient
(b) Volume co-efficient
(c) Bulk modulus
(d) Compressibility
Answer:
(d) Compressibility
Question 3.
The modulus of rigidity of a liquid is
(a) zero
(b) 1
(c) infinite
(d) none of these

Answer:
(a) zero
Question 4.
The Young's modulus of a wire of length $L$ and radius $r$ is $Y$. If the length is reduced to $\frac{L}{2}$ and radius to $\frac{\mathrm{r}}{2}$, its Young's modulus will be ......
(a) $\frac{Y}{2}$
(b) $\mathrm{Y}$
(c) $2 Y$
(d) $4 Y$
Answer:
(b) $\mathrm{Y}$
The Young's modulus is a property of the material. So, it remains the same.
Question 5.
A spherical ball contracts in volume by $0.01 \%$ when subjected to a normal uniform pressure of 100 atmospheres. The bulk modulus of the material of the ball in dynes $/ \mathrm{cm}^2$ is $\ldots \ldots$
(a) $1 \times 10^{12}$
(b) $10 \times 10^{12}$
(c) $100 \times 10^{12}$
(d) $2 \times 10^{11}$
Answer:
(a) $1 \times 10^{12}$
$
\mathrm{B}=\frac{\mathrm{PV}}{\Delta \mathrm{V}}=\frac{100 \times 10^{11} \times 100}{0.01}=1 \times 10^{11} \mathrm{Nm}^{-2}=1 \times 10^{12} \text { dynes } / \mathrm{cm}^2
$
Question 6.
The value of Poisson's ratio lies between
(a) 0 and 1
(b) -0.5 and 1
(c) 0 and 0.5
(d) -1 and 1
Answer:
(c) 0 and 0.5

Question 7.
Poisson's ratio cannot have the value
(a) 0.1
(b) 0.2
(c) 0.5
(d) 0.7
Answer:
(d) 0.7
Question 8.
The bulk modulus for an incompressible fluid is ........
(a) zero
(b) 1
(c) $\infty$
(d) between 0 and 1
Answer:
(c) $\infty$
Question 9.
The breaking stress of a wire depends upon
(a) length of the wire
(b) material of the wire
(c) radius of the wire
(d) shape of the cross-section
Answer:
(b) material of the wire
Question 10 .
Shearing stress causes change in ......
(a) length
(b) breadth
(c) shape
(d) volume
Answer:
(c) shape
Question 11.
A certain force increases the length of a wire by $1 \mathrm{~mm}$. The force required to increases its length by 2 $\mathrm{mm}$ is
(a) $2 \mathrm{~F}$
(b) $4 \mathrm{~F}$
(c) $8 \mathrm{~F}$
(d) $16 \mathrm{~F}$
Answer:
(a) $2 \mathrm{~F}$
$\Delta 1 \propto F$

Question 12.
Two wires of same material, having cross-sectional areas in the ratio $1: 2$ and lengths in the ratio $1: 4$ are stretched by the same force. The ratio of the stresses in the wires will be
(a) $1: 2$
(b) $2: 1$
(c) $1: 4$
(d) $4: 1$
Answer:
(b) $2: 1$
$
\text { Stress }=\frac{\mathrm{F}}{\mathrm{A}} ; \frac{(\text { Stress })_1}{(\text { Stress })_2}=\frac{\mathrm{A}_2}{\mathrm{~A}_1}=\frac{2}{1}
$
Question 13.
If the tension on a wire is removed at once, then
(a) it will break
(b) its temperature will reduce
(c) there will be no change in its temperature
(d) its temperature will increase
Answer:
(d) its temperature will increase
When tension is applied, the distance between the atoms of the wire increases, there by increasing the potential energy of the wire. When the tension is removed, the potential energy decreases. This energy is converted into heat energy. So the temperature of the wire increases.
Question 14.
In steel, the Young's modulus and the strain at the breaking point are $2 \times 10^{11} \mathrm{Nm}^{-2}$ and 0.15 respectively. The stress at the breaking point for steel is therefore
(a) $2 \times 10^8 \mathrm{Nm}^{-2}$
(b) $3 \times 10^{10} \mathrm{Nm}^{-2}$
(c) $3 \times 10^{12} \mathrm{Nm}^{-2}$
(d) None of these

Answer:
(b) $3 \times 10^{10} \mathrm{Nm}^{-2}$
Breaking stress $=$ Breaking strain $\times$ Young's modulus $=0.15 \times 2 \times 10^{11}=3 \times 10^{10} \mathrm{Nm}^{-2}$.
Question 15 .
The pressure in a liquid at a given depth below the surface
(a) is always exerted downward
(b) is the same in all directions
(c) equals the total weight of liquids above that depth
(d) depends upon the amount of liquid below that depth
Answer:
(b) is the same in all directions
Question 16.
The pressure at the bottom of a liquid tank does not depend on .........
(a) acceleration due to gravity
(b) density of the liquid
(c) height of the liquid
(d) area of the liquid surface
Answer:
(d) area of the liquid surface
Question 17.
The pressure of the Earth's atmosphere at sea level is due to the
(a) gravitational attraction of the Earth for the atmosphere
(b) evaporation of water from the seas and oceans
(c) fact that most living things constantly breathe air
(d) heating of the atmosphere by the Sun
Answer:
(a) gravitational attraction of the Earth for the atmosphere

Question 18.
The operating principle of a hydraulic press is
(a) Pascal's Law
(b) Archimedes principle
(c) Newton's law of gravitation
(d) Boyle's law
Answer:
(a) Pascal's Law
Question 19.
A floating body always displaces its own .......
(a) mass of liquid
(b) volume of liquid
(c) weight of liquid
(d) none of these
Answer:
(c) weight of liquid
Question 20.
The pressure in a water tap at the base of a building is $3 \times 10^6$ dynes $/ \mathrm{cm}^2$ and on its top it is $1.6 \times 10^6$ dynes $/ \mathrm{cm}^2$. The height of the building is approximately
(a) $7 \mathrm{~m}$
(b) $14 \mathrm{~m}$
(c) $70 \mathrm{~m}$
(d) $140 \mathrm{~m}$
Answer:
(b) $14 \mathrm{~m}$
$
h=\frac{P_2-P_1}{\rho g}=\frac{1.4 \times 10^6}{1 \times 980}=14.2 \times 10^2 \mathrm{~cm}=14 \mathrm{~m}
$
Question 21.
The weight of a body in air is $100 \mathrm{~N}$. How much will it weight in water, if it displaces $400 \mathrm{cc}$ of water?
(a) $90 \mathrm{~N}$

(b) $94 \mathrm{~N}$
(c) $98 \mathrm{~N}$
(d) None of these
Answer:
(d) None of these
Upthrust $=$ Weight of water displaced $=0.4 \times 9.8=3.92 \mathrm{~N}$
Apparent weight $=100-3.92=96.08 \mathrm{~N}$
Question 22.
A body is floating in a liquid with $\frac{1}{5}$ of its volume outside the liquid. If the relative density of the body is 0.9 , that of the liquid is
(a) $0.9 \times 5$
(b) $0.9 \times \frac{5}{4}$
(c) $0.9 \times \frac{4}{5}$
(d) $0.9 \times 4$
Answer:
$
\frac{\rho_{\text {body }}}{\rho_{\text {liquid }}}=\frac{4}{5} \Rightarrow \rho_{\text {liquid }}=\frac{5}{4} \times 0.9
$
Question 23.
A boat having length $3 \mathrm{~m}$ and breadth $2 \mathrm{~m}$ is floating on a lake. It sinks by $1 \mathrm{~cm}$ when a man gets on it. The mass of the man is ........
(a) $60 \mathrm{~kg}$
(b) $55 \mathrm{~kg}$
(c) $65 \mathrm{~kg}$
(d) $70 \mathrm{~kg}$
Answer:
(a) $60 \mathrm{~kg}$
Weight of man $=$ Weight of additional water displaced $\mathrm{mg}=3 \times 2 \times 0.01 \times 103 \times \mathrm{g} \mathrm{m}=60 \mathrm{~kg}$
Question 24 .
A bird weighs $2 \mathrm{~kg}$ and is inside an airtight cage of $1 \mathrm{~kg}$. If its starts to fly, then what is the weight of the bird and cage assembly?
(a) $3 \mathrm{~kg}$
(b) $2 \mathrm{~kg}$
(c) $1 \mathrm{~kg}$
(d) none of these
Answer:
(a) $3 \mathrm{~kg}$
When the bird flies, the upthrust on it is equal and opposite to the down thrust on the cage. Therefore, the weight of the assembly remains unchanged.

Question 25.
Two light balls are suspended as shown in the figure. When a stream of air passes through the space between them, the distance between the balls will

(a) increase
(b) decrease
(c) remain the same
(d) may increase or decrease depending on the speed of air
Answer:
(b) decrease
When the speed of the air between the balls increases, then according to Bernoulli's theorem, the pressure in this region decreases. Therefore, the balls will be pushed towards each other by the air pressure in the outer region.
Question 26.
The rate of leak from a hole in a tank is .......
(a) independent of its height from the bottom
(b) more if situated near the bottom
(c) more if situated near its top
(d) more at midway between top and bottom
Answer:
(b) more if situated near the bottom
Question 27.
When a fluid passes through the constricted part of a pipe, its ........
(a) velocity and pressure decrease
(b) velocity and pressure increase
(c) velocity decreases and pressure increases
(d) velocity increases and pressure decreases
Answer:
(d) velocity increases and pressure decreases
Question 28.
Bernoulli's principle does not explain
(a) curved path of a spinning ball
(b) surviving of a fish in a lake
(c) working of a paint sprayer
(d) automatic blowing off the roofs of houses during blizzard in hilly areas
Answer:
(b) surviving of a fish in a lake
Question 29.
An ideal liquid flows through a horizontal tube of variable diameter. The pressure is lowest where the
(a) velocity is highest
(b) velocity is lowest
(c) diameter is largest
(d) none of these
Answer:
(a) velocity is highest

Question 30.
Bernoulli's equation is applicable in the case of
(a) streamlined flow of compressible fluids
(b) streamlined flow of incompressible fluids
(c) turbulent flow of compressible fluids
(d) turbulent flow of incompressible fluids
Answer:
(b) streamlined flow of incompressible fluids
Question 31 .
Bernoulli's theorem is based on the conservation of
(a) mass
(b) momentum
(c) energy
(d) all of the above
Answer:
(c) energy
Question 32 .
Bernoulli's theorem is applicable to
(a) flow of liquids
(b) viscocity
(c) surface tension
(d) static fluid pressure
Answer:
(a) flow of liquids
Question 33.
The working of an atomiser depends on ....
(a) Bernoulli's principle
(b) Boyle's law
(c) Archimedes principle
(d) Pascal's law
Answer:
(a) Bernoulli's principle
Question 34.
'Dynamic lift' is related to ......
(a) Bernoulli's principle
(b) Archimedes principle
(c) Equation of continuity
(d) Pascal's law
Answer:
(a) Bernoulli's principle
Question 35.
A gale blows over a house. The force due to the gale on the roof is
(a) in the downward direction

(b) zero
(c) in the upward direction
(d) horizontal
Answer:
(c) in the upward direction
Question 36.
If a stream of air is blown under one of the pans of a physical balance in equilibrium, then the pan will
(a) go up
(b) go down
(c) not be affected
(d) go up or down depending on the velocity of the stream
Answer:
(b) go down
Question 37.
Water venturimeter works on the principle of
(a) Newton's third law of motion
(b) Stokes's formula
(c) Bernoulli's theorem
(d) Hooke's law
Answer:
(c) Bernoulli's theorem
Question 38.
Aeroplanes are made to run on runway before take-off because it
(a) decreases friction
(b) decreases viscous drag of air
(c) decreases atmospheric pressure
(d) provides required life to the aeroplane
Answer:
(d) provides required life to the aeroplane
Question 39.
When the terminal velocity is reached, the acceleration of a body moving through a viscous medium is

(a) zero
(b) positive
(c) negative
(d) either (b) or (c) depending upon other factors.
Answer:
(a) zero
Question 40 .
If a raindrop with a mass of $0.05 \mathrm{~g}$ falls with constant velocity, the retarding force of atmospheric friction is (neglect density of air)
(a) zero
(b) 49 dynes
(c) 490 dynes
(d) none of these
Answer:
(b) 49 dynes
Solution:
Since the rain drop is falling with constant velocity, the retarding upward force is equal to its weight in magnitude, $F=0.05 \times 980=49$ dynes
Question 41.
If temperature rises, the coefficient of viscosity of a liquid .......
(a) decreases
(b) increases
(c) remains unchanged
(d) increases for some liquids and decreases for others
Answer:
(a) decreases
Question 42 .
The velocity of a rain drop attains constant value because of
(a) surface tension
(b) upthrust of air
(c) viscous force exerted by air
(d) air currents
Answer:

(c) viscous force exerted by air
Question 43.
With increase in temperature the viscosity of
(a) a gas decreases and a liquid increases
(b) a gas increases and a liquid decreases
(c) both gases and liquids decrease
(d) both gases and liquids increase
Answer:
(b) a gas increases and a liquid decreases
Question 44.
Two small spheres of radii $\mathrm{r}$ and $2 \mathrm{r}$ fall through a viscous liquid with the same constant speed. The viscous forces experienced by them are in the ratio ........
(a) $1: 2$
(b) $2: 1$
(c) $1: 4$
(d) $4: 1$
Answer:
(a) $1: 2$
$
\mathrm{F}=6 \pi \eta a v ; \frac{\mathrm{F}_1}{\mathrm{~F}_2}=\frac{r_1}{r_2}=\frac{r}{2 r}=\frac{1}{2}
$
Question 45 .
Viscosity is the property of liquids by virtue of which they ......
(a) oppose the relative motion of its parts
(b) push neighbouring molecules
(c) attract other molecules
(d) become conducting
Answer:
(a) oppose the relative motion of its parts

Question 46.
Streamlined flow is more likely for liquids with ........
(a) high density and low viscosity
(b) low density and high viscosity
(c) high density and high viscosity
(d) low density and low viscosity
Answer:
(b) low density and high viscosity
Question 47.
The dimensional formula of coefficient of viscosity is
(a) $\mathrm{M}^0 \mathrm{~L}^{-1} \mathrm{~T}^{-1}$
(b) $\mathrm{M}^0 \mathrm{~L}^2 \mathrm{~T}^{-1}$
(c) $\mathrm{ML}^2 \mathrm{~T}^{-1}$
(d) $\mathrm{ML}^{-1} \mathrm{~T}^{-1}$
Answer:
(d) $\mathrm{ML}^{-1} \mathrm{~T}^{-1}$
Question 48 .
A good lubricant should have
(a) high viscosity
(b) low viscosity
(c) moderate viscosity
(d) high density
Answer:
(a) high viscosity
Question 49.
If a liquid wets a solid surface, the angle of contact is
(a) $0^{\circ}$
(b) $90^{\circ}$
(c) less than $90^{\circ}$
(d) greater than $90^{\circ}$
Answer:
(c) less than $90^{\circ}$
Question 50 .
When some detergent is added to water, the surface tension ........
(a) remains unaffected
(b) increases
(c) decreases
(d) may increase or decrease
Answer:
(c) decreases
Question 51.
Rain drops are spherical because of
(a) gravitational force
(b) surface tension
(c) low viscosity of water

(d) air resistance
Answer:
(b) surface tension
Question 52.
At critical temperature the surface tension of a liquid .......
(a) is zero
(b) is the same as that at any other temperature
(c) is infinity
(d) cannot be determined
Answer:
(a) is zero
Question 53.
A liquid will not wet the surface of a solid if the angle of contact is .....
(a) acute
(b) obtuse
(c) zero
(d) $\frac{\pi}{2}$
Answer:
(b) obtuse
Question 54.
The surface tension of soap solution is $25 \times 10^{-3} \mathrm{Nm}^{-1}$. The excess pressure inside a soap bubble of diameter $1 \mathrm{~cm}$ is ........
(a) $5 \mathrm{~Pa}$
(b) $10 \mathrm{~Pa}$
(c) $20 \mathrm{~Pa}$
(d) None of these
Answer:
(c) $20 \mathrm{~Pa}$
Excess pressure $=\frac{4 \mathrm{~T}}{r}=\frac{4 \times 25 \times 10^{-3}}{0.5 \times 10^{-2}}=20 \mathrm{~Pa}$
Question 55.
Surface tension does not depend on
(a) nature of the liquid
(b) temperature of the liquid
(c) atmospheric pressure
(d) presence of impurities
Answer:
(c) atmospheric pressure

Question 56.
Meniscus of mercury in a capillary is
(a) concave
(b) convex
(c) plane
(d) cylindrical
Answer:
(b) convex
Question 57.
The potential energy of a molecule on the surface of a liquid compared to that of a molecules inside the liquid is
(a) smaller
(b) the same
(c) greater
(d) zero
Answer:
(c) greater
Question 58 .
At which of the following temperatures, the value of surface tension of water is minimum?
(a) $4^{\circ} \mathrm{C}$
(b) $25^{\circ} \mathrm{C}$
(c) $50^{\circ} \mathrm{C}$
(d) $15^{\circ} \mathrm{C}$
Answer:
(d) $15^{\circ} \mathrm{C}$
Question 59.
If the surface tension of water is $0.06 \mathrm{Nm}^{-1}$ then the capillary rise in a tube of diameter $1 \mathrm{~mm}$ is (angle of contact $=0^{\circ}$ )
(a) $1.22 \mathrm{~cm}$
(b) $2.44 \mathrm{~cm}$
(c) $3.12 \mathrm{~cm}$
(d) $3.86 \mathrm{~cm}$

Answer:
(b) $2.44 \mathrm{~cm}$
$
h=\frac{2 \mathrm{~T} \cos \theta}{r \rho g}=\frac{2 \times 0.06 \times 1}{0.5 \times 10^{-3} \times 10^3 \times 9.8}=0.0244 \mathrm{~m} \Rightarrow h=2.44 \mathrm{~cm}
$
Question 60 .
The surface tension phenomenon is the result of the tendency of a system to ........
(a) conserve energy
(b) conserve volume
(c) keep potential energy minimum
(d) keep surface area minimum
Answer:
(c) keep potential energy minimum
2 Mark Questions
II. Write brief answer to the following questions:
Question 1.
What is meant by 'Mean positions of atoms'?
Answer:
The interaction between the atoms, they position themselves at a particular interatomic distance. This position of atoms in this bound condition is called their mean positions.
Question 2.
What is meant by 'Evaporation'?
Answer:
When a liquid is heated at constant pressure to its boiling point or when the pressure is reduced at a constant temperature it will convert to a gas. This process of a liquid changing to a gas is called evaporation.
Question 3.
What are the physical states of matter?

Answer:
Solid, liquid, gas, plasma, Bose-Einstein condensates, quark-gluon plasmas and hot plasma these are the physical states of matter.
Question 4.
Define elasticity? Give its example.
Answer:
A body regains its original shape and size after the removal of deforming force, it is said be elastic and the property is called elasticity. Example: Rubber, metals, steet ropes
Question 5 .
Define deforming force?
Answer:
The force which changes the size or shape of a body is called a deforming force.
Question 6.
Define 'Plasticity'?
Answer:
If a body does not regain its original shape and size after removal of the deforming force, it is said to be a plastic body and the property is called plasticity.
Example: Glass.
Question 7.
Explain the classification of longitudinal stress?
Answer:
Longitudinal stress can be classified into two types, tensile stress and compressive stress. Tensile stress: Internal forces on the two sides of $\Delta \mathrm{A}$ may pull each other, i.e., it is stretched by equal and opposite forces. Then, the longitudinal stress is called tensile stress. Compressive stress: When forces acting on the two sides of $\Delta \mathrm{A}$ push each other, $\Delta \mathrm{A}$ is pushed by equal and opposite forces at the two ends. In this case, $\triangle \mathrm{A}$ is said to be under compression. Then, the longitudinal stress is called compressive stress.
Question 8.
Explain the classification of longitudinal strain?
Answer:
Longitudinal strain can be classified into two types: -

1. Tensile strain: If the length is increased from its natural length then it is known as tensile strain.
2. Compressive strain: If the length is decreased from its natural length then it is known as compressive strain.
Question 9.
Define elastic limit?
Answer:
Elastic limit: The maximum stress within which the body regains its original size and shape after the removal of deforming force is called the elastic limit.
Question 10.
What is meant by "Breaking stress or tensile strength"?
Answer:
The maximum stress ulitimate stress point beyond which the wire breaks is called breaking stress or tensile strength.
Question 11.
Define compressibility?
Answer:
The reciprocal of the bulk modulus is called compressibility. It is defined as the fractional change in volume per unit increase in pressure.
$
\mathrm{C}=\frac{1}{\mathrm{~K}}=\frac{-\varepsilon_v}{\sigma_n}=\frac{-\frac{\Delta \mathrm{V}}{\mathrm{V}}}{\Delta \mathrm{P}}
$
Question 12.
Define relative density (or) specific gravity?
Answer:
The relative density of a substance is defined as the ratio of the density of a substance to the density of water at $4^{\circ} \mathrm{C}$. It is a dimensionless positive scalar quantity.
Question 13.
What is atmospheric pressure?
Answer:
The pressure exerted by the atmosphere at sea level is called atmospheric pressure. The atmospheric pressure at sea level is $1.013 \times 10^5 \mathrm{Nm}^{-2}$ (or) $\mathrm{Pa}$
Question 14.
Explain hydrostatic paradox with suitable example.
Answer:
Hydrostatic paradox: The pressure exerted by a liquid column depends only on the height of the liquid column and not on the shape of the containing vessel:
Let us consider three vessels A, B and $\mathrm{C}$ of different shapes. These vessels are connected at the bottom by a horizontal pipe. When they are filled a liquid (say water), it occupies the same level even though the vessels hold different amount of water. It is true because the liquid at the bottom of each section of the vessel experiences the same pressure.

Question 15 .
Write the examples of floating bodies?
Answer:
1. A person can swim in sea water more easily than in river water.
2. Ice floats on water.
3. The ship is made of steel but its interior is made hollow by giving it a concave shape.
Question 16.
Define 'Viscosity'?
Answer:
Viscosity is defined as 'the property of a fluid to oppose the relative motion between its layers'.
Question 17.
Define tube of flow.
Answer:
A bundle of streamlines having the same velocity over any cross section perpendicular to the direction of flow then such bundle is called a 'tube of flow'.
Question 18.
Write down the applications of viscosity?
Answer:
(i) The oil used as a lubricant for heavy machinery parts should have a high viscous coefficient. To select a suitable lubricant, we should know its viscosity and how it varies with temperature. [Note: As temperature increases, the viscosity of the liquid decreases]. Also, it helps to choose oils with low viscosity used in car engines (light machinery).
(ii) The highly viscous liquid is used to damp the motion of some instruments and is used as brake oil in hydraulic brakes.
(iii) Blood circulation through arteries and veins depends upon the viscosity of fluids.
(iv) Millikan conducted the oil drop experiment to determine the charge of an electron. He used the knowledge of viscosity to determine the charge.

Question 19.
What is meant by'Molecular range'?
Answer:
It is the maximum distance upto which a molecule can exert force of attraction on another molecule. It is of the order of $10^{-9} \mathrm{~m}$ for solids and liquids.
Question 20.
What is sphere of influence?
Answer:
It is a sphere drawn around a particular molecule as centre and molecular range as radius.