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Physical Quantities and Measurement ICSE Concise Selina

Physical Quantities and Measurement ICSE Class-8th Concise Selina Physics Solutions Chapter-2. We Provide Step by Step Answer of Objective, True False , Fill in the blanks,Match the following , Short/Long Answer,Numerical Type of Exercise-2 Matter. Visit official Website  CISCE  for detail information about ICSE Board Class-8.

Physical Quantities and Measurement ICSE Concise Selina


A. Objective Questions Chapter-2 Physical Quantities and Measurement ICSE

1. Write true or false for each statement

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(a) Equal volumes of the two different substances have equal masses.
Answer False.
Equal volumes of the two different substances have different masses.

(b) The density of a piece of brass will change by changing its size or shape.
Answer False.

(c) The density of a liquid decreases with increase in its temperature.
Answer True.

(d) Relative density of water is 1.0.
Answer True.

(e) Relative density of a substance is expressed in g cm-3.
Answer False.
Relative density of a substance has no units.

(f) When a body is immersed in a liquid, the buoyant force experienced by the body is equal to the volume of the liquid displaced by it.
Answer False.
The buoyant force is equal to the weight of the liquid displaced by the immersed part of body.

(g) A body experiences the same buoyant force while floating in watr or alcohol.
Answer True.

(h) A body experiences the same buoyant force when it floats or sinks in water.
Answer False.

(i) A body floats in a liquid when its weight becomes equal to the weight of the liquid displaced by its submerged part. .
Answer True.

(j) A body while floating, sinks deeper in a liquid of low density than in a liquid of high density.
Answer True.

2. Fill in the blanks

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(a) 1 kg is the mass of 1000 ml of water at 4°C.
(b) Mass = density x volume.
(c) The S.I. unit of density is Kg m-3
(d) Density of water is 1000 Kg m-3.
(e) 1 g cm-3 = 1000 Kg m-3.
(f) The density of a body which sinks in water is more than 1000 Kg m-3.
(g) Abody sinks in a liquid A, butt floats in a liquid B. The density of liquid A is less than the density of liquid B.
(h) A body X sinks in water, but a body Y floats on water. The density of the body X is more than the density of body Y.
(i) The buoyant force experienced by a body when floating in salt¬water is equal to or same that of when floating in pure water.
(j) The weight of a body floating in a liquid is zero.

3. Match the following

Match the following

4. Select the correct alternative 

(a) The correct relation is

  1. Density = Mass x Volume
  2. Mass = Density x Volume
  3.  Volume = Density x Mass
  4. Density = Mass + Volume

Answer

Mass = Density x Volume

(b) The relative density of alcohol is 0.8. Its density is

  1.  0.8
  2. 800 kg nr3
  3.  800 g cm-3
  4. 0.8 kg m-3

Answer

800 kg nr3

(c) A block of wood of density 0.8 g cm-3 has a volume of 60 cm3. The mass of block is

  1.  60.8 g
  2.  75 g
  3. 48 g
  4. 0.013 g

Answer

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48 g

(d) The density of aluminium is 2.7 g cm-3 and that of brass 8.4 g cm’3. The correct statement is

  1. Equal masses of aluminium and brass have equal volumes
  2. The mass of a certain volume of brass is more than the mass of equal volume of aluminium.
  3.  The volume of a certain mass of brass is more than the volume of equal mass of aluminium.
  4.  Equal volumes of aluminium and brass have equal masses.

Answer

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The mass of a certain volume of brass is more than the mass of equal volume of aluminium.

(e) A density bottle has a marking 25 mL on it. It means that:

  1.  the mass of density bottle is 25 g
  2. the density bottle will store 25 ml of any liquid in it
  3. density bottle will store 25 ml of water, but more volume of liquid denser than water.
  4.  the density bottle will store 25 ml of water, but more volume of a liquid lighter than water.

Answer

(f) The correct statement is

  1.  The buoyant force on a body is equal to the volume of the liquid displaced by it ‘
  2. The buoyant force on a body is equal to the volume of the body
  3. buoyant force on a body is equal to the weight of the liquid displaced by it
  4.  The buoyant force on a body is always equal to the weight of the body.

Answer

The buoyant force on a body is equal to the weight of the liquid displaced by it

(g) A piece of wood floats on water. The buoyant force on wood will be

  1.  zero
  2.  more than the weight of the wood piece
  3. equal to the weight of the wood piece
  4. less than the weight of the wood piece.

Answer

The buoyant force on a body is equal to the weight of the liquid displaced by it

(h) The weight of a body is more than the buoyant force experienced by it, due to a liquid. The body will

  1. sink
  2.  float with its some part outside the liquid
  3. It float just below the surface of liquid
  4. float with whole of its volume above the surface of liquid.

Answer

sink

B. Short/Long Ans Questions

Question 1.


Define the term density of a substance.
Answer:
Density of a substance is defined as “Mass per Unit volume”.

Density

Question 2.


Name the S.I. unit of density. How is it related to g Cm-3 ?
Answer:
S.I. unit of density is kg M-3 In C.GS. system unit of mass is g and unit of volume is Cm3, so CGS unit of density is g Cm-3 (gram per cubic centimetre)
Relationship between S.I. and C.GS. units

Relationship between S.I. and C.GS. units

Question 3.


The density of brass is 8.4 g cm-3. What do you mean by this statement ?
Answer:
This statement meAns one cubic centimetre volume of brass has mass of 8.4 g.

Question 4.


Arrange the following substances in order of their increasing density:
Iron, Cork, Brass, Water, Mercury.
Answer:
Cork, Water, Iron, Brass, Mercury.

Question 5.


How does the density of a liquid (or gas) vary with temperature?

Answer:


Most of the liquids increase in volume with increase in temperature, but water shows anomalous behaviour. Water has maximum volume at 4°C and maximum density at 4°C.
Actually, when volume increases density decreases and when volume decreases the density increases.
But water when cooled from a high temperature, contracts upto 4°C because volume decreases and expands when cooled further below 4°C and hence density of water increases when it is cooled upto 4°C while decreases when cooled further below 4°C. In other words, the density of water is maximum at 4°C equal to 1 g Cm-3 or lOOO kg m-3.

Question 6.


A given quantity of a liquid is heated. Which of the following quantity will vary and how ?
(a) mass, (b) volume and (c) density
Answer:
When a given quantity of liquid is heated
(a) Mass : does not change.
(b) Volume: changes and increases with rise in temperature.
(c) Density : Changes and decreases.
Density = Mass / volume

Question 7.


Describe an experiment to determine the density of the material of a coin.
Answer:
Density = Mass / volume
To find the density of the material of a coin, we need to find its (i) mass—by common beam balance and (ii) Its volume by measuring cylinder.
Measure the mass of coin.
EXPERIMENT – Let the mass of coin shown by beam balance = M (gram) = 50 g (ray)
Measure the vol. of coin.
Initial volume of water = V1 = 40 ml (say)
Final volume of water
When coin is added in the cylinder=V2 = 50 ml (say)
Then vol. of coin = V2 – V1 = 50 – 40 = 10 ml

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