ICSE Class 8CISCE
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# Selina solutions for Class 8 Physics chapter 2 - Physical Quantities and Measurement

## Chapter 2: Physical Quantities and Measurement

#### Selina solutions for Class 8 Physics Chapter 2 [Page 0]

Write true or false

Equal volumes of the two different substances have equal masses.

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The density of a piece of brass will change by changing its size or shape.

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The density of a liquid decreases with increase in its temperature.

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Relative density of water is 1.0.

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Relative density of a substance is expressed in g cm-3.

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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.

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A body experiences the same buoyant force while floating in watr or alcohol.

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A body experiences the same buoyant force when it floats or sinks in water.

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A body floats in a liquid when its weight becomes equal to the weight of the liquid displaced by its submerged part.

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A body while floating, sinks deeper in a liquid of low density than in a liquid of high density.

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1 kg is the mass of ............ml of water at 4°C.

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Mass = density x .........

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The S.I. unit of density is ..........

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Density of water is .......Kg m-3.

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1 g cm-3 = ......... Kg m-3.

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The density of a body which sinks in water is .........than 1000 Kg m-3.

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A body sinks in a liquid A, butt floats in a liquid B. The density of liquid A is .......than the density of liquid B.

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A body X sinks in water, but a body Y floats on water. The density of the body X is.........than the density of body Y.

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The buoyant force experienced by a body when floating in salt¬water is ....... to or same that of when floating in pure water.

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The weight of a body floating in a liquid is ........

Match the following :

 Column A Column B (a) kg  m^-3 (i) relative density (b) no unit (ii) sinks in alcohol (c) relative density (iii) floats on water (d) iron (iv) density (e) wood (v) density bottle

Select the correct alternative

The correct relation is

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

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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

Select the correct alternative

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

Select the correct alternative

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.

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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.  the 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.

Select the correct alternative

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. The 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.

Select the correct alternative

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.

Select the correct alternative

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.  float just below the surface of liquid
4. float with whole of its volume above the surface of liquid.

#### Selina solutions for Class 8 Physics Chapter 2 [Page 0]

Define the term density of a substance.

Name the S.I. unit of density. How is it related to g Cm-3 ?

The density of brass is 8.4 g cm-3. What do you mean by this statement ?

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

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

A given quantity of a liquid is heated. Which of the following quantity will vary and how ?
(a) mass, (b) volume and (c) density

Describe an experiment to determine the density of the material of a coin.

Describe an experiment to determine the density of a liquid.

What is a density bottle ? How is it used to find the density of a liquid ?

Define the term relative density of a substance.

What is the unit of relative density ?

Distinguish between density and relative density.

Explain the meaning of the statement ‘relative density of aluminium is 2.7’ ?

How does the density of a body and that of a liquid determine whether the body will float or sink into that liquid ?

A cork piece floats on water surface while an iron nail sinks in it. Explain the reason.

Which of the following will sink or float on water ? (Density of water = 1 g Cm-3)
(a) body A having density 500 kg m-3

Which of the following will sink or float on water ? (Density of water = 1 g Cm-3)

body B having density 2520 kg m-3

Which of the following will sink or float on water ? (Density of water = 1 g Cm-3)

body C having density 1100 kg m-3

Which of the following will sink or float on water ? (Density of water = 1 g Cm-3)

body D having density 0.85 g m-3

What is the law of floatation ?

The density of water is 1.0 g Cm-3. The density of iron is 7.8 × 10″3 g Cm-3. The density of mercury is 13.6 g Cm-3.
Ans the following:
Will a piece of iron float or sink in water ?

The density of water is 1.0 g Cm-3. The density of iron is 7.8 × 10″3 g Cm-3. The density of mercury is 13.6 g Cm-3.
Ans the following:
(b) Will a piece of iron float or sink in mercury ?

The diagram given below show a body floating in three different liquids. A, B and C at different levels.
(a) In which liquid does the body experience the greatest buoyant force ?
(b) Which liquid has the least density ?
(c) Which liquid has the highest density ?

For a floating body, how is its weight related to the buoyant force ?

Why does a piece of ice float on water ?

Explain why an iron needle sinks in water, but a ship made of iron floats on water.

It is easier to swim in sea water than in river water. Explain the reason.

Icebergs floating on sea water are dangerous for ships. Explain the reason.

Explain why it is easier to lift a stone under water than in air.

What is a submarine ? How can it be made to’dive in water and come to the surface of water.

A balloon filled with hydrogen rises in air. Explain the reason.

#### Selina solutions for Class 8 Physics Chapter 2 [Page 0]

The density of air is 1.28 g/Iitre. Express it in:
(a) g cm3

The density of air is 1.28 g/Iitre. Express it in:
kg m

The dimensions of a hall are 10 m × 7 m × 5 m. If the density of air is 1.11 kg m-3, find the mass of air in the hall.

The density of aluminium is 2.7 g cm3. Express it in kg m-3

The density of alcohol is 600 kg m-3. Express it in g Cm-3.

A piece of zinc of mass 438.6 g has a volume of 86 Cm3. Calculate the density of zinc.

A piece of wood of mass 150 g has a volume of 200 Cm3. Find the density of wood ¡n
(a) C.GS. unit,

A piece of wood of mass 150 g has a volume of 200 Cm3. Find the density of wood ¡n
S.l. unit

Calculate the volume of wood of mass 6000 kg if the density of wood is 0.8 g Cm-3

Calculate the density of solid from the following data :
(a) Mass of solid = 72 g
(b) Initial volume of water in measuring cylinder = 24 ml
(c) Final volume of water when solid is completely immersed in water = 42 ml

The mass of an empty density bottle is 21.8 g, when filled completely with water is 41.8 g and when filled completely with liquid it is 40.6 g. Find :
(a) the volume of density bottle.

(b) the relative density of liquid.

From the following observations, calculate the density and relative density of a brine solution. Mass of empty density
bottle = 22 g
Mass of bottle + water = 50 g
Mass of bottle + brine solution = 54 g

The mass of an empty density bottlfe is 30 g, it is 75 g when filled completely with water and 65 g when filled completely with a liquid. Find volume of density bottle.

The mass of an empty density bottle is 30 g, it is 75 g when filled completely with water and 65 g when filled completely with a liquid. Find  density of liquid.

The mass of an empty density bottle is 30 g, it is 75 g when filled completely with water and 65 g when filled completely with a liquid. Find  relative density of liquid.

## Selina solutions for Class 8 Physics chapter 2 - Physical Quantities and Measurement

Selina solutions for Class 8 Physics chapter 2 (Physical Quantities and Measurement) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CISCE Selina Concise Physics - Middle School for Class 8 solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 8 Physics chapter 2 Physical Quantities and Measurement are Measurement of Density of Irregular Solids Using Eureka Can, Measurement of Density of Irregular Solids Using - Measuring Cylinder, Concept of Measurement of Density of Fluids, Concept of Flotation and Sinking of a Substance (Relate to Density), Comparison of Densities in the Three States of Matter..

Using Selina Class 8 solutions Physical Quantities and Measurement exercise by students are an easy way to prepare for the exams, as they involve solutions arranged chapter-wise also page wise. The questions involved in Selina Solutions are important questions that can be asked in the final exam. Maximum students of CISCE Class 8 prefer Selina Textbook Solutions to score more in exam.

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