Question # 1

In an 𝑎 −decay:

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The parent and daughter nuclei have same number of protons

The daughter nucleus has one proton more than parent nucleus

The daughter nucleus has two protons less than parent nucleus

The daughter nucleus has two neutrons more than parent nucleus

The threshold frequency depends on the nature on:

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Natural frequency

Photosensitive anode

Photosensitive cathode

Photon

The angle of projection, at which the range of projectile would become half of its maximum value.

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45Degree

30Degree

15Degree

60 Degree

When the velocity of a body is doubled:

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Its K.E is doubled

Its P.E is doubled

Its momentum is doubled

Its acceleration is doubled

In photoelectric effect, if we increase the frequency of the incident light then of the electrons increased

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Number

K.E

P.E

Frequency

A particle revolves round a circular path with a constant speed. The accelerationof the particle is

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A. A long the circumference of the circle

Along the tangent

Along the radius

Zero

The pressure exerted on the walls on the vessel by gas molecules is defined as:

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Force per unit volume

Energy per unit area

mass per unit volume

None of these

If a source of emf is traversed from positive to negative the potential change will be:

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Positive

Negative

Zero

Constant

For atomic nucleus, the binding energy per nucleon with increase in mass number:

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Increases continuously

Remains same

Decrease continuously

First increases and then decreases with increase in mass number

Of electron of 50 keV strike a heavy target. Then radiation emitted by target will be

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Visible light

Radio waves

Ultraviolet

None of these

A magnetic field

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Always exerts a force on a charged particle

Never exerts a force on a charged particle

Exerts a force on a charged particle if it is moving across the magnetic lines of force

Exerts a force on a charged particle if it is moving along the magnetic lines of force.

In the absence of air resistance, a stone is thrown from P and follows a parabolic path in which the highest point reached is T. The vertical component of acceleration of stone is:

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Zero at T

Greatest at T

) Greatest at P

the same at P as at T

A particle is moving with constant speed by keeping itself at constant distance from a fixed point in a given plane. Its motion is

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Circular motion

Uniform circular motion

Uniform circular motion with fixed axis of rotation

Uniform circular motion with axis of rotation not defined

The phenomenon of radioactivity is associated with:

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Fission of nucleus

Disintegration of neutrons

Emission of spectral lines

Spontaneous disintegration of the nuclei of atoms

The more readily fissionable isotope of uranium has an atomic mass of:

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220

230

235

240

The rate of change of momentum of a body falling freely under gravity is equal to its

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Impulse

Kinetic energy

Pover

Weight

A body of mass m tied to a string is moved in a vertical circle of radius r. the difference in tensions at the lowest point and the highest point is.

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2 mg

4 mg

6 𝑚g

8 mg

For a particle moving in uniform circular motion

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Velocity is transverse and acceleration is radical

Velocity is radial and acceleration is transverse

Both velocity and acceleration are radial

Both velocity and acceleration are transverse

Magnetic field inside a solenoid is:

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) Directly proportional to current

Inversely proportional to current

Directly proportional to its length

Inversely proportional to total no of turns

In full wave rectification, the output DC voltage across the load is obtained for.

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The positive half cycle of input AC only

The negative half cycle of input AC

The completes cycle of input AC only

All of the above

De-Broglie received the Nobel prize in

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1929

1937

1928

1924

For the same value of resistors the output of non-inverting amplifier compared to the output of inverting amplifier is, (ignoring phase difference)

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Greater

Equal

Smaller

Undefined

If temperature of the sink is decreased, efficiency of a carnot engine.

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Remains constant

Decreases

Increases

None of these

When heat is added to the system, the entropy change is:

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Positive

Negative

Zero

None of these

In a gravitational field when work done by gravity is negative then

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P.E increases

P.E decrease

None

P.E remains same

No of spark plugs needed in diesel engine is:

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Four

Five

Six

None of these

If the range of a projectile is R, the potential energy will be maximum after the projectile has covered (from start) distance equal to:

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R/2

R/4

R

R/9

In a one-dimensional elastic collision, the relative velocity of approach before collision is equal to:

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Sum of the velocities of the bodies

e times the relative velocity of separation after collision

1⁄𝑒 times the relative velocity of separation after collision

relative velocity of separation after collision

For a particle in circular motion the centripetal acceleration

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may be more or less than its tangential acceleration

equal to its tangential acceleration a

more than its tangential acceleration

less than its tangential acceleration

On slightly disturbing a body which is an unstable equilibrium, its center of gravity

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rises

falls

remains constant

first rises then falls

While dealing with the processes i thermodynamics, the working substances is usually:

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Oxygen gas

Hydrogen gas

Ideal gas

None of these

In the theory of dimensional analysis, heat may be properly represented by:

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ML²T^-2

MT^-2

ML^-1T^-1

None of these

A straight current carrying conductor experiences maximum forces in a uniform magnetic field when it is placed:

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Parallel to the field

Perpendicular o the field

At an angle of 45 to the field

None of these

If the momentum of a body is increased n times, its kinetic energy increases:

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n times

2 n times

√𝑛 times

n 2 time

Photo cells is a device which convert light into:

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Wave nature

Particle nature

Particle wave nature

Dual nature

Two railway trucks of masses m and 3m move towards each other in opposite directions with speeds 2v and v respectively. These trucks collide and stick together. What is the speed of the trucks after the collision?

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v/4

v/2

v

5v/4

A 100W, 220V bulb is operated on a 110V line, the power consumed is:

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25W

75W

50W

100W

A boy is travelling from Lahore to Karachi with uniform velocity . Its

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Speed changes

Acceleration changes

Direction of motion changes

Displacement from origin changes

A piece of Aluminium (Al) and a piece of Germanium (Ge) are cooled T1 K to T2 K. The resistance of:

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Each of them increases

Each of them decreases

Al increases and Ge decreases

Al decreases and that of Ge increases

𝑎, 𝖰 𝒂𝒏𝒅 radiations come out of radioactive substance:

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Spontaneously

When it is put in a reactor

When it is heated

Under pressure

The magnetic field produced due to the current in a straight wire is proportionalto the :

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Electric current

Conducting material

Length of the wire

Diameter of the wire