Objective type questions,Class 8 , ch 2 -Physical quantities Measurement

Density & Floatation Interactive Practice

A. OBJECTIVE TYPE QUESTIONS (MCQs)

Q1. The correct relation between density, mass and volume is:

(i) Density = Mass × Volume
(ii) Mass = Density × Volume
(iii) Volume = Density × Mass
(iv) Density = Mass + Volume

(ii) Mass = Density × Volume

Q2. The relative density of alcohol is 0.8. Its density is:

(i) 0.8
(ii) 800 kg m⁻³
(iii) 800 g cm⁻³
(iv) 0.8 kg m⁻³

(ii) 800 kg m⁻³

Q3. A block of wood of density 0.8 g cm⁻³ has a volume of 60 cm³. The mass of the block is:

(i) 60.8 g
(ii) 75 g
(iii) 48 g
(iv) 0.013 g

(iii) 48 g

Q4. The density of aluminium is 2.7 g cm⁻³ and that of brass is 8.4 g cm⁻³. The correct statement is:

(i) Equal masses have equal volumes
(ii) Brass has more mass for equal volume
(iii) Brass has more volume for equal mass
(iv) Equal volumes have equal masses

(ii) The mass of brass is more for equal volume

Q5. Equal volumes of aluminium and brass have equal masses. (True/False)

False

Q6. A density bottle has a marking 25 mL on it. It means that:

(i) Mass is 25 g
(ii) It stores 25 mL of any liquid
(iii) Only water can be stored
(iv) Stores different volumes

(ii) It stores 25 mL of any liquid

Q7. The correct statement is:

(i) Buoyant force = volume displaced
(ii) Buoyant force = volume of body
(iii) Buoyant force = weight of liquid displaced
(iv) Buoyant force = weight of body

(iii) Weight of liquid displaced

Q8. A piece of wood floats on water. The buoyant force acting on it is:

(i) Zero
(ii) More than weight
(iii) Equal to weight
(iv) Less than weight

(iii) Equal to weight

Q9. If the weight of a body is more than the buoyant force, the body will:

(i) Sink
(ii) Float partially
(iii) Float below surface
(iv) Float above surface

(i) Sink

B. FILL IN THE BLANKS

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

1000

Mass = density × __________

volume

The SI unit of density is __________

kg m⁻³

Density of water is __________ kg m⁻³

1000

1 g cm⁻³ = __________ kg m⁻³

1000

A body that sinks has density __________ than water

greater

If body sinks in A but floats in B, density of A is __________ than B

less

Density of X is __________ than Y

greater

Buoyant force in salt water is __________ than pure water

more

Weight of floating body is __________ to buoyant force

equal

C. TRUE / FALSE

Equal volumes of different substances have equal masses

False

Density depends on shape

False

Density decreases with temperature

True

Relative density of water is 1

True

Relative density has unit

False

Buoyant force equals volume displaced

False

Same buoyant force in water and alcohol

False

Same buoyant force floating/sinking

False

Floating condition is correct

True

Body sinks more in less dense liquid

True

D. MATCH THE FOLLOWING

Match Column A with Column B:

(a) kg m⁻³
(b) No unit
(c) Relative density
(d) Iron
(e) Wood

(i) relative density
(ii) sinks in alcohol
(iii) floats on water
(iv) density
(v) density bottle

(a) → (iv)
(b) → (i)
(c) → (i)
(d) → (ii)
(e) → (iii)