If the density of water is $$1g\,{cm}^{-3}$$ in CGS system, its value in MKS system is __________.

$${10}^{3}$$ $$kg$$ $${m}^{-3}$$

$${10}^{-3}$$ $$kg$$ $${m}^{-3}$$

$${10}^{-6}$$ $$kg$$ $${m}^{-3}$$

A body has a free fall from a height of $$20m$$. After falling through a distance of $$5m$$, the body would have ___________.

lost one-fourth of its total energy

lost one-fourth of its potential energy

gained one-fourth of its potential energy

gained three-fourth of its total energy

MCQ Questions for Class 8 General Knowledge Basic Science Quiz 3

Fahrenheit and Celsius are the two scales used for measuring temperature. If the numerical value of a temperature recorded in both the scales is found to be same, what is the temperature?

0%
$-40^o$
0%
$+40^o$
0%
$+72^o$
0%
$-72^o$

Explanation

Let T be the temperature.

\frac{9}{5} C + 32

$\dfrac{9}{5} C + 32$

put F=C=T

T=-40

Which one of the following statements is not correct?

0%
The SI unit of charge is ampere-second
0%
Debye is the unit of dipole moment
0%
Resistivity of a wire depends on its length and breadth
0%
The kinetic energy of an electron of mass m kg and charge e coulomb, when accelerated through a potential difference of V volt, is eV joule

With respect to the new initiative by the government regarding air pollution - AQI, choose the correct statement(s).
It aims to monitor the air quality of four metro cities only.
It is a real-time measuring process.
Dark red colour indicates the severe condition of air quality.
Select the correct answer using the codes given below.

0%
1 and 3
0%
Only 3
0%
1, 2 and 3
0%
2 and 3

Match List I with List II and select the correct answer using the code given below the Lists:

List I (Element)	List II (Use)
A. Li	Time keeper in atomic clocks
B. Na	Batteries
C. K	Transfer of nerve impulses
D. Cs	Control of the water content in the blood

0%
A-2, B-3, C-4, D-1
0%
A-1, B-2, C-3, D-4
0%
A-2, B-4, C-3, D-1
0%
A-1, B-3, C-2, D-4

Which component is formed by plants in the ecosystem ________________.

0%
Decomposer
0%
Consumer
0%
Producer
0%
All of the above

Which of the following pairs is wrong?

0%
Pressure - Barometer
0%
Relative density - Pyrometer
0%
Temperature - Thermometer
0%
Earthquake - Seismograph

Explanation

Pyrometer is an instrument used for measurement of temperature.

So, option

B

$B$ is incorrect.

Match the columns:

List I (Quantity)	List II (Unit)
(A) Luminous intensity	(1) Kelvin
(B) Amount of substance	(2) Candela
(C) Time	(3) Second
(D) Temperature	(4) Mole

0%
A-2; B-4; C-3; D-1
0%
A-4; B-2; C-3; D-1
0%
A-2; B-4; C-1; D-3
0%
A-3; B-1; C-4; D-2

Match the columns:

Quantity	Dimensions
(A) Velocity	(1) $\left[ ML{ T }^{ -2 } \right]$
(B) Force	(2) $\left[ L{ T }^{ -1 } \right]$
(C) Work	(3) $\left[ M{ L }^{ 2 }{ T }^{ -2 } \right]$
(D) Momentum	(4) $\left[ ML{ T }^{ -1 } \right]$

0%
A-2; B-1; C-3; D-4
0%
A-3; B-4; C-1; D-2
0%
A-2; B-1; C-4; D-3
0%
A-4; B-3; C-2; D-1

The displacement of a particle at time is given by

x = a j + b j + \frac{c}{2} t^{2} k

$x=aj+bj+\cfrac { c }{ 2 } { t }^{ 2 }k$
where

a, b, c

$a,b,c$ are positive constants. Then the particle is _________.

0%
accelerated along k-direction
0%
decelerated along k-direction
0%
decelerated along j-direction
0%
accelerated along j-direction

The SI unit of acceleration is _______.

0%
${ ms }^{ -1 }$
0%
${ ms }^{ -2 }$
0%
$c{ ms }^{ -2 }$
0%
$k{ ms }^{ -2 }$

Masses of stars and galaxies are usually expressed in terms of _______.

0%
neutron mass
0%
earth's mass
0%
solar mass
0%
lunar mass

Which of the following physical quantities is dimensionless?

0%
Strain
0%
Angle
0%
Specific gravity
0%
All of these

Consider the physical quantities
(1) Electric current (2) Work
(3) Temperature (4) Density
Which of the above are scalar quantities?

0%
1, 2 and 3
0%
1. 4 and 3
0%
3, 4 and 2
0%
1, 2, 3 and 4

One light year is approximately equal to ________.

0%
${10}^{11}km$
0%
${10}^{15}m$
0%
${10}^{16}m$
0%
${10}^{16}km$

If the density of water is

1 g {c m}^{- 3}

$1g\,{cm}^{-3}$ in CGS system, its value in MKS system is __________.

0%
$1$ $kg$ ${m}^{-3}$
0%
${10}^{3}$ $kg$ ${m}^{-3}$
0%
${10}^{-3}$ $kg$ ${m}^{-3}$
0%
${10}^{-6}$ $kg$ ${m}^{-3}$

The force required to keep a body in uniform circular motion is ________.

0%
centripetal force
0%
centrifugal force
0%
resistance
0%
None of these

The motion of a car along a straight path is shown by the following figure.
The car starts from

O

$O$ and reaches at

A

$A$ ,

B

$B$ and

C

$C$ at different instants of time. During its motion from

O

$O$ to

C

$C$ and back to

B

$B$ , the distance covered and the magnitude of the displacement are respectively

0%
$25km$ and $60km$
0%
$95km$ and $35km$
0%
$60km$ and $25km$
0%
$85km$ and $35km$

Consider the following statements.
(1) All plane angles are measured in radian.
(2) All the solid angles are measured in steradian.
Which of the following statements given above is/are correct?

0%
Only 1
0%
Only 2
0%
2 and 3
0%
1,2, and 3

Two stones of unequal masses are thrown vertically up with the same velocity. Which of the following will happen?

0%
The heavier mass will reach greater height
0%
The lighter mass will reach greater height
0%
Both will reach the same height
0%
Any of them may reach greater height

A person is sitting in a moving train and facing the engine. He tosses up a coin and coin falls behind him. It can be concluded that the train is _________.

0%
moving forward and gaining speed
0%
moving forward and losing speed
0%
moving forward with uniform speed
0%
moving backward with uniform speed

A piece of paper and a cricket ball are dropped from the same height. Under which of the following conditions do both reach the surface simultaneously?

0%
They must have the same volume
0%
They must have the same density
0%
They must have the same mass
0%
They must be dropped in vacuum

For a particle revolving in a circular path with constant speed, the acceleration of the particle is __________.

0%
along the tangent
0%
along the radius
0%
zero
0%
along the circumference of the circle

For a moving body, at any instant of time, __________.

0%
if the body is not moving, the acceleration is necessarily zero
0%
if the body is slowing, the retardation is negative
0%
if the body is slowing, the distance is negative
0%
if displacement, velocity and acceleration at that instant are known, we can find the displacement at any given time in future

Explanation

(A) Suppose throwing a ball vertically up. At the highest point. It is at momentary rest

(V = O)

$(V=O)$ i but acceleration

g

$g$ still acts downwards.

So, (A) is incorrect.

(B) A slowing body has positive retardation.

(D) From second law of kinematics,

x = x_{0} + u t + \frac{1}{2} a t^{2}

$x=x_0+ut+\dfrac{1}{2}at^2$ .

By knowing

u, a

$u, a$ and

x_{0}

$x_0$ at instant

t = 0

$t=0$ we can determine

x

$x$ at any

t

$t$ .

Which one of the following statements is not correct?

0%
If the velocity and acceleration have opposite sign, the object is slowing down
0%
If the velocity is zero at an instant, the acceleration should also be zero at that instant
0%
If the velocity is zero for a time interval, the acceleration is zero at any instant within the time interval
0%
So,the position and velocity have opposite sign the object is moving towards the origin

If the distance

S

$S$ covered by a moving car in rectilinear motion with a speed

v

$v$ in time

t

$t$ is given by

S = v t

$S=vt$ , then the car undergoes ___________.

0%
a uniform acceleration
0%
a non-uniform acceleration
0%
a uniform velocity
0%
a non-uniform velocity

A body has a free fall from a height of

20 m

$20m$ . After falling through a distance of

5 m

$5m$ , the body would have ___________.

0%
lost one-fourth of its total energy
0%
lost one-fourth of its potential energy
0%
gained one-fourth of its potential energy
0%
gained three-fourth of its total energy

A brick is thrown vertically from an aircraft flying two kilometers above the Earth. The brick will fall with a ________.

0%
constant speed
0%
constant velocity
0%
constant acceleration
0%
constant speed for some time then with constant acceleration as it nears the Earth

Assertion (A) Pulling a lawn roller is easier than pushing it.
Reason, (R) Pushing increases the apparent weight and hence the force of friction.

0%
Both A and R are true and R is the correct explanation of A
0%
Both A and R are true and R is not the correct explanation of A
0%
A is true, but R is false
0%
A is false, but R is true

Water flows out of the hole of a bucket and follows a parabolic path. If the bucket falls freely under gravity, the water flow (ignoring air resistance) ___________.

0%
follows a straight line path relative to the falling bucket
0%
follows a parabolic path relative to the falling bucket
0%
stops
0%
decreases but continues to flow

A motor vehicle is moving on a circle with a uniform speed. The net acceleration of the vehicle is ________.

0%
zero
0%
towards the centre of the circle
0%
away from the centre along the radius of the circle
0%
perpendicular to the radius and along the velocity

CBSE Questions for Class 8 General Knowledge Basic Science Quiz 3 - MCQExams.com

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Practice Class 8 General Knowledge Quiz Questions and Answers

CBSE Questions for Class 8 General Knowledge Basic Science Quiz 3 - MCQExams.com

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Practice Class 8 General Knowledge Quiz Questions and Answers

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