JAMB UTME - Physics - 1985 | Green Bridge CBT

Question 1 Report

An electric kettle, connected to a 240V mains, produces 6.0 x 105J of heat energy to boil a quantity of water in 5 minutes. Find the resistance of the kettle.

14.4

Ω

28.8

Ω

144

Ω

288

Ω

2880

Ω

Answer Details

Heat energy = Electrical energy

6 x 105 = $\frac{V^{2}}{R}$ t

R = $\frac{240 \times 240 \times 5 \times 60}{6 \times 105}$

= 28.8 $Ω$

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Read lesson note on Heat Energy (WAEC)

Current Electricity

Heat Energy

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Question 2 Report

A wire P has half the diameter and half the length of a wire Q of similar material. The ratio of the resistance of P to that of Q is

8 : 1

4 : 1

2 : 1

1 : 1

1 : 4

Answer Details

Resistance

α

\frac{l e n g t h}{a r e a}

$\frac{R_{Q}}{R_{P}}$ = $\frac{L_{Q} A_{P}}{L_{P} A_{Q}}$

LQ = 2LP

DQ = 2DP

AP = $π$ $\frac{(2 D_{P})^{2}}{2}$

= $π$ DP

AQ = $π$ $\frac{(D_{P})^{2}}{2}$

= $\frac{1}{4}$ $π$ DP

therefore, $\frac{R_{Q}}{R_{P}}$ = $\frac{2 L_{P} \times π D_{P}}{L_{P} \times \frac{1}{4} π D_{P}}$

= 2 : 1

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Capacitors

Current Electricity

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Question 3 Report

A good calorimeter should be of

low specific heat capacity and low heat conductivity

low specific heat capacity and high heat conductivity

high specific heat capacity and low heat conductivity

dull surface and low heat conductivity

Temperature And Its Measurement

Pressure

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Question 4 Report

Which of the following is NOT a fundamental S.I unit?

Meter

Ampere

Kelvin

Seconds

Radian

Fundamental And Derived Quantities And Units

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Question 5 Report

A uniform cylindrical block of wood floats in water with one-third of its height above the water level, in a liquid of relative density 0.8, what fraction of its height will be above the liquid level?

1

6

1

5

1

3

4

5

\frac{5}{6}

Answer Details

Height inside H2O =

\frac{2}{3}

R.d = $\frac{height inside H_{2} O}{height inside liquid}$

0.8 = $\frac{\frac{2}{3}}{X}$

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Question 6 Report

Which of the following features is NOT a characteristic of natural radioactivity?

Radioactivity is a nuclear phenomenon

Radioactivity is exhibited only by elements of mass number greater than 206

The radioactivity of an element is affected by electric and magnetic fields in the surroundings

Radioactive substances emits three types of radiations, a-rays,

β

-rays and y-rays

The radioactive element is transformed into a new element

Properties Of Waves: Reflection, Refraction, Diffraction

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Question 7 Report

A transformer has a primary coil with 500 turns and a secondary coil with 2500 turns. When the voltage input to the primary coil is 120V, the output is

6000V

600V

240V

60V

24V

Answer Details

For transformers,

\frac{V_{p}}{V_{s}}

=

\frac{N_{p}}{N_{s}}

=

\frac{I_{p}}{I_{s}}

$\frac{500}{2500}$ = $\frac{120}{V_{s}}$

Vs = 600v

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Current Electricity

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Question 8 Report

Normal atmospheric pressure at sea-level is 105Nm-2 and the acceleration due to gravity is approximately 10ms-1. If the atmosphere has a uniform density of 1kgm-3, its height is

100m

1000m

10 000m

100 000m

1000 000m

Pressure

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Question 9 Report

If the distance between two stationary charged particle is doubled, the magnitude of the electro-static force between them will be

doubled

halved

a quarter of its former value

unchanged

four times the original value

Answer Details

F

α

\frac{1}{d^{2}}

F x d2 = constant

F1 x (d1)2 = F2 x (d2)2

d2 = 2d1

F1 x (d1)2 = F2 x (2d1)2

F2 = $\frac{1}{4}$ F1

Read lesson note on Electrostatics (JAMB)

Electrostatics

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Question 10 Report

A force of 100N stretches an elastic string to a total length of 20cm. If an additional force of 100N stretches the string 5cm further, Find the natural length of the string

15cm

12cm

10cm

8cm

5cm

Answer Details

Using, f1 = f2

e1 = 20 - L ; e2 = 5cm

$\frac{f_{1}}{e_{1}}$ = $\frac{f_{2}}{e_{2}}$

$\frac{100}{20 - L}$ = $\frac{100}{5}$

hence, L = 15cm

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Elasticity

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Question 11 Report

Two divers G and H are at depths 20m and 40m respectively below the water surface in a lake. The pressure on G is P₁ while the pressure on H is P₂. If the atmospheric pressure is equivalent to 10m of water, then the value of $ \frac{p_2}{p_1} $ is

0.50

0.60

1.67

2.00

3.0

Answer Details

pressure at H = 40m ; pressure at G, p1 = 20m

$\frac{p_{1}}{p_{1}}$ = $\frac{40}{20}$

= 2

Read lesson note on Temperature And Its Measurement (JAMB)

Read lesson note on Pressure (JAMB)

Read lesson note on Measurements And Units (JAMB)

Temperature And Its Measurement

Pressure

Measurements And Units

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Question 12 Report

Water shows anomalous behaviour

below 0oC

between 0oC and 4oC

at exactly 4oC

between 4oC and 100oC

above 100oC

Heat Energy

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Question 13 Report

Which of the following phenomena CANNOT be explained by the molecular theory of matter?

Expansion

Conduction

Convection

Radiation

Evaporation

Waves

Structure Of Matter And Kinetic Theory

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Question 14 Report

Which of the following statements about electrolysis is NOT correct?

The substances in solution in the electrolyte become ionized

Ions are electrically charged and are attracted towards electrodes when a potential difference is applied

Ions may be discharged at the electrodes, forming bubbles or deposits

The mass deposited depends upon the length of time for which current flows

The mass of gas set free or metal deposited is proportional to the square of the current

Properties Of Waves: Reflection, Refraction, Diffraction

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Question 15 Report

On which of the following does the operation of a moving coil ammeter depend? i. Electromagnetic induction ii. Force on a carrying-current conductor iii. Magnetic effect of an electric current

i only

ii only

iii only

ii and iii only

i,ii and iii

Electric Field

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Question 16 Report

A metal block of mass 5kg lies on a rough horizontal platform. If a horizontal force of 8N applied to the block through its center of mass just slides the block on the platform, then the coefficient of limiting friction between the block and platform is

0.16

0.63

0.80

1.60

2.00

Answer Details

F =

μ

R

= $μ$ mg

8 = $μ$ x 5 x 10

$μ$ = 0.16

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Friction

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Question 17 Report

A simple pendulum with a period of 2.0s has its length doubled. Its new period is

1.00s

1.41s

0.3s

2.83s

4.00s

Answer Details

Using

\frac{T_{1}}{T_{2}}

=

\sqrt{\frac{L_{1}}{L_{2}}}

$\frac{2}{T_{2}}$ = $\sqrt{\frac{L_{1}}{2 L_{1}}}$

T2 = 2.83sec

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Question 18 Report

A thin aluminum plate has a surface area of 1500m at 20oC. What will be its surface area when it is cooled to -20oC? (Take the linear expansivity of aluminum to be 2.5 x 10-5k-1).

1.503m2

1.500m2

1.498m2

1.497m2

1.490m2

Answer Details

β

= A2 - A1

2 X 10-5 x 2.5 = $\frac{A_{2} \times 1.5}{1.5 \times (- 20 - 20)}$

A2 = 1.498m2

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Question 19 Report

An object is placed 15cm in front of a concave mirror of radius 40cm. The image formed

virtual and 60cm behind the mirror

real and 60cm behind the mirror

virtual and at infinity

real and at infinity

virtual and 40cm from the mirror

Reflection Of Light At Plane And Curved Surfaces

Properties Of Waves: Reflection, Refraction, Diffraction

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Question 20 Report

Which of the following will convert a milliammeter to a voltmeter?

low series resistance

low parallel resistance

high series resistance

high parallel resistance

parallel resistance equal to milliammeter resistance

Electrostatics

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Question 21 Report

Which of the following is NOT a force?

Friction

Tension

Upthrust

Weight

Impulse

Equilibrium Of Forces

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Question 22 Report

If the fundamental frequency of a closed pipe organ on a day when the speed of sound is 340ms-1 is 170Hz, then the length of the pipe is

50cm

70cm

100cm

150cm

200cm

Answer Details

λ

=

\frac{v}{f}

= $\frac{340}{170}$

= 2m ; for closed pipe

L = $\frac{1}{4}$ $λ$

= $\frac{1}{4}$ x $\frac{2}{1}$

= 0.5m

= 50cm

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Current Electricity

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Question 23 Report

Two thermo flasks of volume $V_x$ and $V_y$ are filled with liquid water at an initial temperature of 0^oC. After sometime the temperature were found to be $\theta_x$, $\theta_y$, respectively. Given that $\frac{V_x}{V_y}=2$ and $\frac{\theta_x}{\theta_y}=\frac{1}{2}$ the ratio of the heat flow into the flask is

1

4

1

2

4

1

2

Answer Details

Heat = mc

θ

Hx = Dx x Vx x Cx x $θ$ x

Hy = Dy x Vy x Cy x $θ$ y

$\frac{H_{x}}{H_{y}}$ = $\frac{D_{x} \times V_{x} \times C_{x} \times θ_{x}}{D_{x} \times V_{x} \times C_{x} \times θ_{x}}$

= 2 x $\frac{1}{2}$

= 1

Read lesson note on Quantity Of Heat (JAMB)

Quantity Of Heat

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Question 24 Report

Two liquids, P at a temperature of 20oC and Q at a temperature of 80oC have specific heat capacities of 1.0Jkg-1oC-1 and 1.5J kg-1oC-1respectively. if equal masses of P and Q are mixed in a lagged calorimeter, then the equilibrium temperature is

44oC

50oC

56oC

60oC

70oC

Answer Details

Heat lost = heat gained

m x (80 - $θ$ ) x 1.5 = m x ( $θ$ - 20) x 1

$θ$ = 56oC

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Temperature And Its Measurement

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Question 25 Report

A cell gives a current of 0.15A through a resistance of $8\ \Omega$ and 0.3A. When the resistance is changed to $3\ \Omega$ the internal resistance of the cell is

0.05

Ω

1.00

Ω

1.50

Ω

2.00

Ω

2.50

Ω

Current Electricity

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Question 26 Report

A narrow beam of white light can be split up into different colours by a glass prism. The correct explanation is that

white light is an electromagnetic wave

the prism has all the colours of the white light

white light has undergone total internal reflection in the prism

different colours of white light travel with different speeds in glass

white ligth consist of yellow, green and red colours

Light Waves

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Question 27 Report

The graph in the fig above describes the motion of a particle. the acceleration of the particle during the motion is

0.00ms-2

0.25ms-2

4.00ms-2

8.00ms-2

10.00ms-2

View Answer

Question 28 Report

In the Fig above, MN is a light uniform meter rule pivoted at O, the 80cm mark. A load of mass 3.00kg is suspended on the meter rule at L, the 10cm mark. If the rule is kept in equilibrium by a string RP, fixed at P and attached to the rule at R, the 20cm mark, then the Tension T on the string is

3.0N

3.4N

3.5N

6.0N

7.0N

Equilibrium Of Forces

Measurements And Units

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Question 29 Report

A block of mass 2.04kg resting on a smooth horizontal plane is acted upon simultaneously by two-forces, 10N due North and 10N due East. The magnitude of the acceleration produced by the force on the block is

0.10ms-2

7.07ms-2

10.00ms-2

14.10ms-2

20.00ms-2

Answer Details

R =

\sqrt{10^{2} + 10^{2}}

R = 14.14N

R = F = ma

14.14 = 2 x a

a = 7.07ms-1

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Read lesson note on Equilibrium Of Forces (WAEC)

Scalars And Vectors

Equilibrium Of Forces

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Question 30 Report

In order to find the depth of the sea, a ship sends out a sound wave and receives an echo after one second. If the velocity of sound in water is 1500ms-1, what is the depth of the sea?

0.75km

1.50km

2.20km

3.00km

3.75km

Answer Details

Echo time = 1

\div

2 = 0.5sec

depth = velocity x time

= 1500 x 0.5

= 750m = 0.75km

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Sound Waves

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Question 31 Report

A 45o triangular glass prism can be used as a reflector of light because

A refraction never takes place in such a prism

the angle of reflection equals the angle of incidence

the refractive index of glass is less than 1

it is transparent

the critival angle angle for glass is less than 45o

Reflection Of Light At Plane And Curved Surfaces

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Question 32 Report

Two rays of light from a point below the surface of water are equally inclined to each other at $60^\circ$ in water. What is the angle between the rays when they emerge into air? (Take the refractive index of water to be $\frac{4}{3}$)

41.8o

44.1o

60.0o

83.6o

120.0o

Answer Details

\frac{4}{3}

=

\frac{s i n r_{1}}{s i n 30}

and

\frac{4}{3}

=

\frac{s i n r_{2}}{s i n 30}

r1 = 41.8o and r2 = 41.8o

angle between them = r1 + r2

= 83.6o

Read lesson note on Refraction Of Light Through Plane And Curved Surfaces (JAMB)

Refraction Of Light Through Plane And Curved Surfaces

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Question 33 Report

A 0.05kg bullet travelling at 500ms-1 horizontally strikes a thick vertical wall. It stops after penetrating through the wall horizontal distance of 0.25m. What is the magnitude of the average force the wall exerts on the bullet?

25N

50N

250N

500N

25 000N

Answer Details

F = ma

= m $\frac{(v^{2} - u^{2})}{2 s}$

F = 0.05 $\frac{(0 - (500)^{2})}{2 \times 0.25}$

F = 25 000N

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Current Electricity

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Question 34 Report

A metal cube of volume 103mm3 is lowered into a measuring cylinder containing water. If the internal cross-sectional area of the cylinder is 1.5 x 102mm2, by how much does the water level rise in the cylinder?

6.67 x 100mm

8.50 x 102mm

1.15 x 103mm

2.50 x 103mm

1.50 x 105mm

Answer Details

Height =

\frac{v o l u m e}{a r e a}

= Height = $\frac{10^{3}}{1.5 \times 10^{2}}$

= 6.67mm

Read lesson note on Measurements And Units (JAMB)

Measurements And Units

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Question 35 Report

In a gas experiment, the pressure of the gas is plotted against the reciprocal of the volume of the gas at a constant temperature. the unit of the slope of the resulting curve is

force

force/m

work

force/m3

energy/m3

Answer Details

slope = pressure

\div

\frac{1}{v o l u m e}

= $\frac{N}{m^{3}}$ x $\frac{m^{3}}{1}$

= Nm = work

Read lesson note on Gas Laws (JAMB)

Gas Laws

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Question 36 Report

A charge of one coulomb liberates 0.0033g of copper in an electrolytic process. How long will it take a current of 2A to librate 1.98g of copper in such a process?

5 mins

30 mins

50 mins

60 mins

120 mins

Electrostatics

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Question 37 Report

A quantity of gas occupies a certain volume when the temperature is -73oC and the pressure is 1.5 atmospheres. If the pressure is increased to 4.5 atmospheres and the volume is halved at the same time, what will be the new temperature of the gas?

573oC

327oC

300oC

110oC

27oC

Answer Details

\frac{P_{1} V_{1}}{T_{1}}

=

\frac{P_{2} V_{2}}{T_{2}}

V1 = 2V2

$\frac{1.5 \times 2 V_{2}}{- 73 + 273}$ = $\frac{4.5 \times V_{2}}{T_{2}}$

T2 = 300K = 27oC

Read lesson note on Quantity Of Heat (JAMB)

Quantity Of Heat

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Question 38 Report

Which of the following statements are true about the spring balance and the chemical balance? i. both are used to measure the mass of an object. ii. either of them may be used to measure the weight of an object. iii. the spring balance works on the principle of Hooke's law while the chemical balance works on the principle of moments. iv. a change in gravity does the readings of a spring balance but not that of a chemical balance.

i, and iv

ii and iii

ii and iv

i, ii and iii

i and iii

Elasticity

Equilibrium Of Forces

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Question 39 Report

If a car starts from rest and moves with a uniform acceleration of 10ms-2 for ten seconds, the distance it covers in the last one second of its motion is

95m

100m

500m

905m

1000m

Answer Details

Distance in 105, using, x = ut +

\frac{1}{2}

at2

x = (0 x 10) + ( $\frac{1}{2}$ x 10 x 10 x 10) = 500m

distance in 9s; x - (0 x 9) + ( $\frac{1}{2}$ x 10 x 9 x 9) = 405m

distance in last is = difference

= 500 - 405

= 95m

Read lesson note on Motion (JAMB)

Motion

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Question 40 Report

Which of the following types of motion are oscillatory? i.a diving board when used by a diver. ii. the motion of the balance wheel of a wrist watch. iii. the motion of the turn-table of a record player. iv. the motion of the center of a ten kobo piece as it rolls down an inclined plane. v. the motion of the needle of a D.C. ammeter into which a low A.C. current is passed

i and ii

i, ii and iii

i, ii and iv

i, ii and v

iii, iv and ii

Scalars And Vectors

Simple Harmonic Motion

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Question 41 Report

In the Fig above, Current I passes through the combination, if the power dissipated in the 5 ohm resistor is 40W, then the power dissipated in the 10 ohm resistor is

10W

20W

40W

80

100W

Current Electricity

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Question 42 Report

The areas of the effort and load pistons of a hydraulic press are 0.5m2 and 5m2 respectively. If a force F1 of 100N is applied on the effort piston, the force F2 on the load is

10N

100N

500N

1000N

5000N

Answer Details

\frac{l o a d}{a r e a}

=

\frac{e f f o r t}{a r e a}

$\frac{l o a d}{5}$ = $\frac{100}{0.5}$

load = 1000N

Read lesson note on Position, Distance And Displacement (WAEC)

Position, Distance And Displacement

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Question 43 Report

What is the number of neutrons in the Uranium isotope $ {}^{238}_{92}X $?

92

146

238

330

119

Structure Of The Atom (Nigeria Only)

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Question 44 Report

Which of the following methods CANNOT be used to produce a steel magnet? The

passing of an electric current through a solenoid

repeated stroking of the specimen with a magnet

repeated stroking of the specimen in opposite directions with magnets

heating of the specimen

hammering of the specimen in the earth's magnetic field

Magnets And Magnetic Fields

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Question 45 Report

Which of the following statements is NOT correct?

A galvanometer can be converted to an ammeter with a different range by connecting a high resistance in series

An electric current always produces a magnetic field

Maxwell's screw rule states that if a corkscrew moves inthe direction of the current, the hand turns in the direction of the lines of force

Electromagnets are used in electric bells and telephone recievers

The lines of force round a straight current carrying conductor are circular

Description Property Of Fields

Current Electricity

Electric Field

Change Of State

Force On A Current-Carrying Conductor In A Magnetic Field

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Question 46 Report

Which of the following statements is NOT correct?

The average range of distinct vision for a normal eye is from the far distance (infinity) up to about 25cm in front of the eye

Longsighted people have difficulty in making the eye lense sufficiently powerful to focus on nearby objects

Shortsighted people cannot accommodate distant objects

Longsighted people need diverging spectacle lenses

A person with long sight has his eye-ball too short and the image of an object is therefore formed behind the retina

Scalars And Vectors

Temperature And Its Measurement

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Question 47 Report

Which of the following statements are NOT correct?

boiling occurs when the saturated vapour pressure of the liquid involved equals the external pressure

both the boiling point and the saturated vapour pressure of a given liquid depends on the external pressure

the saturated vapour presssure rises with increase in temperature

the saturated vapour pressure is independent of the volume available for the vapour

it is possible to boil water at a lower temperature than 100oC at high altitude

Quantity Of Heat

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Question 48 Report

A convex mirror is used as a driving mirror because i. its image is erect. ii. it has a large field of view. iii. it has a long focal length. Identify the CORRECT statement(s)

i andiii only

i and ii only

ii and iii only

i, ii, and iii only

i only