Objective questions of chapter 2(physical quantities and measurement) of class 8

 1. Write true or false for each statement:

A) equal volumes of two different substances have equal masses.

Ans false.

Equal volumes of two different substances have unequal masses.

B) the density of a piece of brass will change by changing its size or shape.

Ans. False

The density of a piece of brass will not change by changing its size or shape.

C) the density of a liquid decreases with increase in its temperature.

Ans. True.

D) relative density of water is 1.0

Ans. True.

E) relative density of a substance is expressed in gram per centimetre cube.

Ans.  false.

Relative density of a substance is a unit less quantity.

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.

Ans. False.

When a body is immersed in a liquid,the buoyant force experienced by the body is equal to the weight of the liquid displaced by it.

G) a body experiences the same buyont force while floating in water or alcohol.

Ans. True.

H) a body experiences the same buoyant force when it floats or sinks in water.

Ans. False.

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

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

Ans. True.

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

Ans. True

2. Fill in the blanks:

A) 1 kg is the mass of..1000..... mL of water at 4°C.

B) Mass= densit × .... volume...

C) the SI unit of density is....kgm-³....

D) density of water is...1000... kgm-³

E)1gcm-³ = ...1000... kgm-³

F) the density of a body which sinks in water is...more.. than 1000 kgm-³.

G) a body sinks in a liquid A, but 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... Then the density of body Y.

I) the buoyant force experienced by a body when floating in salt water is... equal to... That when floating in pure water.

J) the weight of a body floating in a liquid is.. zero....

3. Match the following:

A) kgm-³                  density

B) No unit               relative density

C) relative density   density bottle

D) iron                      sinks in alcohol

E) wood                   floats on water

4. Select the correct alternative:

A) the correct relation is

1. Density=mass×volume

2. Mass=density×volume

3. Volume=density×mass

4. Density=mass+volume

B) the relative density of alcohol is 0.8 . Its density is

1. 0.8

2. 800 kgm-³

3.800gcm-³

4.  0.8 khm-³

C) a block of wood of density 0.8gcm-³ has a volume of 60 cm³. The mass of block is

1. 60.8 g

2. 75 g

3. 48 g

4.  0.013g

D) the density of aluminium is 2.7 gcm-³ and that of brass is 8.4 gcm-³. The correct statement is:

1. Equal masses of aluminium and brass have equal.

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.

E) a density bottle has a marking 25ml 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 water will store 25 ml of water,but more volume of a liquid lighter than water.

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.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.

G) a piece of wood floats on water. 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.

H) 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.