Explore topic-wise InterviewSolutions in .

This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

101.

Explain the following. a] Why is tungsten used almost exclusively for filament of electric lamps? b] Why are the conductors of electric heating devices, such as bread-toasters and electric irons made of an alloy rather than a pure metal? c] Why is the series arrangement not used for domestic circuits? d] How does the resistance of a wire vary with its area of cross-section? e] Why are copper and aluminum wires usually employed for electricity transmission?

Answer»

Solution :a] Tungsten has very high melting POINT `[3380^(@)C]`. So, it can.t melt up to a high temperature. This is the reason why tungsten is used almost exclusively for filament of electric lamps.
b] RESISTIVITY of an alloy is generally higher than that of its constituent metals.
c] Tn series arrangement, the potential drop is divided into different appliances. So, some appliance can not get sufficient potential drop for its PROPER working. This is possible only in parallel connection. Hence, series arrangement is not used for domestic circuits.
d] The resistance of a WIRE is INVERSELY proportional to its area of cross-section,
`RpropI/A`
e] Copper and aluminum have low resistivity. Therefore, there will be less energy loss. Hence, they are usually employed for electricity transmission.
Discussion
102.

What does the statement, 'latent heat of fusion for ice is 80 cal/g' mean?

Answer»

Solution :The statement MEANS that amount of HEAT required to convert l g of ICE at `0^(@)C` into 1 g of water at `0^(@)C` is 80 CALORIES.
Discussion
103.

Refractive index depends on the…………of light.

Answer»

Solution :Velocity.
Explanation : The refractive INDEX of a medium is inversely proportional to the velocity of light. It means as the refractive index of a medium increases, the SPEED of light GOING through that medium DECREASES.
Discussion
104.

List two non conventional sources of energy

Answer»

SOLUTION :Geothermal , SOLAR., BIOMASS, water, wind are the NON CONVENTIONAL sources of energy.
Discussion
105.

Distinguish between linear, cubical and superficial expansion.

Answer»

SOLUTION :
Discussion
106.

Give symbols of (i) an electric cell, (ii) battery of cells.

Answer»

SOLUTION :
Discussion
107.

The rear side of a truck is open and a box of 40 kg mass is placed 5m away from the open end. The coefficient of friction between the box and the surface below it is 0.15 on a straight road, the truck starts from rest and accelerates with 2"m/s"^2. At what distance from the starting point does the box fall off the truck ?

Answer»

Solution :Force on the box due to accelerated motion of the truck `F= ma =40 XX 2= 80 N` (in forward direction)
Reaction on the box, F= R= 80 N (in BACKWARD direction)
Force of limiting friction, `f=muR=0.15 xx 40 xx 10=60N`
Net force on the box in backward direction is P =F'-f
=80-60=20N
Backward acceleration in the box `=a=P/m= (20)/(40)= 0·5"ms"^(-1)`
t= time taken by the box to travel s= 5m and falls off the truck, then from `s=ut+1/2 at^(2)`
`5=0 xx t +1/2 xx 0.5xx t^(2)`
t=4.47 s
If the truck travels a distance X during this time
then `x=0 xx 4.34 +1/2 xx 2 xx (4.471)^(2)`
x=19.98
Discussion
108.

When 'm' kg of a substance of specific heat capacity 'c' J// °C kg cools from temperature 'T' to 'To', how much heat energy will be lost by it?

Answer»

Solution : HEAT ENERGY LOST by the SUBSTANCE `= " MC " (T - T_(o))" J "`
Discussion
109.

Both the statements are true.

Answer»

Both the STATEMENTS are FALSE.
STATEMENT - I is TRUE and statement - II is false.
Statement - I is false and statement - II is true.

Answer :A
Discussion
110.

Assertion : Diamond glitters brilliantly. Reason :Diamond does not absorb sunlight.

Answer»

Both assertion and reason are true and reason is CORRECT EXPLANATION of assertion.
Both assertion and reason are true but reason is not the correct explanation of assertion.
Assertion is true but reason is false
Both assertion and reason are false

Solution :Both assertion and reason are true and reason is correct explanation of assertion.
Discussion
111.

An object is placed at a distance equal to 2f in front of a convex lens. Draw a labelled ray diagram to show the formation of image. State two characteristics of the image formed.

Answer»

SOLUTION :i. A convex lens FORMS real, diminished and inverted image when an object is placed beyond `2F_(1)`.
ii. Consider an object AB shown in figure. A ray AO PASSING through optical centre goes undeviated as ray OA': Similarly, the ray AP, incident parallel to principal axis passes through FOCUS `F_(2)` after refraction and meets the ray OA' at A'. This forms an image A'B'.
iii. This image is formed between `F_(2) and 2F_(2)`.
Discussion
112.

What are the laws of reflection?

Answer»

SOLUTION :There are three LAWS of reflection
1. The angle of reflection is EQUAL to the angle of incidence .
2. The incident ray, the REFLECTED ray and the normal lie in the same plane.
3. The incident ray and the reflected ray are on the opposite sides of the normal.
Discussion
113.

In radioactive radiation, which one is travel with the speed of light …….

Answer»

SOLUTION :GAMMA RADIATION
Discussion
114.

___________ radioactivity can be controlled.

Answer»

SOLUTION :ARTIFICIAL
Discussion
115.

The Ganga runs its course from Gangotri to Ganga Sagar in the Bay of Bengal about how many kilometeres.

Answer»

`2500`
`3500`
`4500`
`2000`

ANSWER :A
Discussion
116.

To find the image-distance for varying object-distances in case o fa convex lens, a student obtains on a screen a sharp image of a bright object places very far from the lens.After that he gradually moves the object towards the lens and each time focuses its image on the screen. (a) In which direction-towards or away from the lens, does he move the screen to focus the object ? (b) What happens to the size of image - does it increase or decrease? (c ) What happen when he moves the objectvery close to the lens ?

Answer»

Solution :(a) He MOVES the SCREEN away from lens to focus the object.
(B) The size of the image increases.
(c ) When the object is places very close to the lens, then image will be formed on the screen. As now image formed is ERECT and VIRTUAL.
Discussion
117.

If the magnitude of two vectors are 3 and 4 and their scalar product is 6, find angle between them and also find |vecA xx vecB|.

Answer»

SOLUTION :`vecA. vecB=AB cos THETA,|vecA XX vecB|=AB SIN theta`
or `6 = (3xx4)cos theta"" = 3xx4 xx sin 60^(@)`
`or theta =60^(@)"" =3xx4xx(SQRT(3))/(2)=6sqrt(3)`
Discussion
118.

Name the process by which nuclear energy is generated and also name one substance used for it. Give two advantages and two hazards of nuclear energy.

Answer»

Solution :The PROCESS is NUCLEAR fission.
Substances are uranium, PLUTONIUM, thorium.
Advantages :
(i) For a given amount of fuel, the amount of energy released is extraordinarily large.
(ii) Nuclear power plants can be set up at any place.
Hazards :
(i) Improper nuclear waste storage and disposal result
in environmental CONTAMINATION.
(ii) Further there is a risk of accidental leakage of nuclear RADIATION.
Discussion
119.

ANTIBIOTICS

Answer»

Solution :To CONTROL the bacterial DISEASES. Eradicating both GRAM positive and Gram NEGATIVE bacteria and thereby control diseases and their epidemics.
Discussion
120.

What are the effects of that disaster on local and surrounding conditions?

Answer»

SOLUTION :During disasters flods the effects on the local and surrounding conditions are as follows:
a. There is WATER logging in many parts of the city.
b. Houses and vehicles get damaged and even submerged in some areas.
c. The flood also affects flights, trains and bus services.
d. The water loging further leads to traffic JAMS in SEVERAL parts of the city.
e. Schools and offices may remain closed.
f. Also, poer cuts occur in several parts of the city in order to prevented electrocution.
Discussion
121.

A force of 50 N is applied on a nail of area 0.001 sq. cm. Then the thrust is

Answer»

50N
100N
0.05N
10N

Answer :A
Discussion
122.

State and explain the lens formula.

Answer»

Solution :1. The RELATIONSHIP between DISTANCE of the object (u). Distance of image (v) and focal length (f) is CALLED as the less formula. Here, distances should be measured according to singn CONVENTION.
2. The lens formula is GIVEN as : `1/v - 1/u = 1/f `
Discussion
123.

The focal length of …………… of compound microscope is bigger than ……………. Lens.

Answer»


ANSWER :eyepicec, OBJECTIVE
Discussion
124.

Electrons as well as protons are responsible for flow of electric currentthrough a conductor.

Answer»

SOLUTION :False- Only electrons are RESPONSIBLE for FLOW of electric CURRENT through a conductor.
Discussion
125.

The gravitational pull of the moon causes the sea-water to rise periodically. (a) What name is given to the condition of the sea when its water is raised ?(b) What name is given to the condition of the sea when its raised water recedes ? (c ) What name is given to the energy which can be harnessed from this natural phenomenon ?(d) Draw labelled diagram to show how this energy can be harnessed from this natural phenomenon ?

Answer»


ANSWER :(a) High TIDE(b)Low tide(C ) Tidal energy
Discussion
126.

Explain: (i). Zone refining (ii). Column chromatography.

Answer»

Solution :The METAL obtained by chemical reduction contains IMPURITIES . The PROCESS of elctrolysis method is used to obtain pure metals from impure metals is KNOWN as refining.
Discussion
127.

Find the equivalent resistance between A and B in the circuit shown in the fig. (a).

Answer»


ANSWER :`4.1 OMEGA`
Discussion
128.

Name the prominent ecologist who is responsible for Chipko movement.

Answer»

SOLUTION :SHRI SUNDARLAL BAHUGUNA.
Discussion
129.

Find out about the traditional systems of water harvesting / management in your region.

Answer»

SOLUTION :The TRADITIONAL system of water harvesting / management in our region are PONDS , pits and LAKES where rainwater is STORED.
Discussion
130.

Refractive index of glass is 1.5 and that of water is 1.3. If the speed of light in water is 2.25xx10^8m/s. What is the speed of light in glass?

Answer»

Solution :Here `n_g=1.5` and `n_w=1.3` LET `v_1` and `v_2` be the speeds of light in glass and WATER RESPECTIVELY. If c is the speed of light in AIR then
`c//v_1=1.5`and`c//v_2=1.3` then,`V_1//v_2=1.3//1.5`
`v_1=1.3//1.5xx2.25xx10^8`
`v_1=1.95xx10^8m//s`
Speed of light in glass is `1.95xx10^8m//s`
Discussion
131.

Distance of the centre of mass of a solid uniform cone from its vertex is z_0 . If the radius of its base is R and its height is h then z_0is equal to:

Answer»

`b^(2)/(4R)`
`(3B)/(4)`
`(5h)/8`
`(3H^(2))/(8R)`

Solution :Mass of elementary disc,
`DM = pir^(2)` dze

`r/R = z/h rArr r =(Rz)/h`
`Z_(0) =(int zdm)/(int dm) =(int_(0)^(h) pi r^(2) dzez)/(1/3 pi R^(2) he) = 3/4 h`
Discussion
132.

List the important products of the Chlor-alkali process. Write one important use of each.

Answer»

Solution :1. Chlorine
2. Hydrogen
3. Sodium Hydroxide
Uses :
1. Chlorine : Water TREATMENT, PVC, CFCs
2. Hydrogen : `NH_3` for fertilisers, FUELS, Margarine
3. NaOH : De-greasing METALS, Paper making
Discussion
133.

An electric motor takes 5A from a 220V line. Determine the power of the motor and the energy consumed in 2h.

Answer»

Solution :It is given that CURRENT drawn by ELECTRIC MOTOR `I=5A` the line voltage `V=220V` and TIME t=2h
`therefore`Power of the motor `P=VI=220V times 5A=1100W`
and the energy consumed `E=Pt=1100W times 2h=2200W h or 2.2kWh`
Discussion
134.

Assertion: there is no effects on other end when one end of the rod is only heated. reason: Heat always flow from a region of lower temperature tohigher temperature of the rod.

Answer»

both the ASSERTION and the REASON are trueand the reason is the CORRECT explanation of the assertion.
both theassertion and the reason are true , but the reason is not the correct explanation of the assertion.
Assertion is true, but Reason is false.
Assertion is false, but the reason is true.

Solution :HEAT always flow from a region of higher temperature to lower temperature.
Assertion is true and the reason is false.
Discussion
135.

Blue, Black,Green,Red

Answer»


ANSWER :Black.It is not a COMPONENT of whit light, WHIL the REST are the COMPONENTS.
Discussion
136.

An electric bulb is connected to 250 volts. If the current of 0.5 A passes through it, what is the power of the bulb?

Answer»


Solution :GIVEN:`"Potential DIFFERENCE (V) = 250 V,"`
Current (I) = 0.5 A
To find: `""` power (P)
FORMULA: `""P=VI `
Calculation : `""`From formula,
`P=250xx0.5`
`therefore"P = 125 W"`
Discussion
137.

What are magnetic field lines ? List two characteristics of these lines. Describe in brief an activity to study the magnetic field lines due to a current flowing in a circular coil.

Answer»

Solution :MAGNETIC filed lines are REPRESENTATION of the magnetic field path along which an imaginary free north pole WOULD tend to MOVE. The tangent at any point on the magnetic field line gives the direction of the magnetic field at that point.
(i) Emerge at north pole and merge at south pole. Inside the magnet, the direction of field lines is from south pole of magnet to its north pole and are closed curves.
(ii) At the points where the magnetic field is stronger, field lines are crowded and vice-versa.
Discussion
138.

At what distance a watch maker must hold his lens from the watch?

Answer»

at the FOCAL LENGTH
at LESS than focal length
at more than the focal length
at zero DISTANCE.

Answer :B
Discussion
139.

Give reasons Veins have valves whereas arteries do not.

Answer»

Solution :VEINS have blood at very low pressure SINCE they are CARRYING blood from body parts back to heart. So to prevent BACKFLOW they have valves.
Discussion
140.

The rays of light travelling through the optical centre of a lens pass without changing their path.

Answer»

Solution :The portion of a lens near the OPTICAL centre is like a very thin SLAB of glass. HENCE, the rays of light travelling through the optical centre of a lens PASS without changing their PATH.
Discussion
141.

If a convex lens of focal length 20 cm and a concave lens of focal length 30 cm are kept in contract with each other. What will the power of the combination ?

Answer»

SOLUTION :`P=5/3`D=1.667 D (APPROXIMATELY)
Discussion
142.

Assertion : A convex lens made of two different materials, A point object is placed on the principal axis, two images formed.Reason:Two images formed by convex lens is always 'virtual'.

Answer»

Both assertion and REASON are TRUE and reason is correct EXPLANATION of assertion.
Both assertion and reason are true but reason is not the correct explanation of assertion.
Assertion is true but reason is FALSE
Both assertion and reason are false

Solution :Assertion is true but reason is false
Discussion
143.

What is fossilization?

Answer»

Solution :The process of formation of fossil in the ROCKS is called fossilization. The COMMON methods of fossilization includes PETRIFACTION, molds and cast, carbonization, PRESERVATION, compression and infiltration.
Discussion
144.

The group of compounds which dissociate partially in aqueous solutions is

Answer»

HYDROCHLORIC ACID, Nitric acid
Carbonic acid, Phosphoric acid
Sodium CHLORIDE, ACETIC acid
Copper sulphate, Sugar solution

Answer :B
Discussion
145.

"Two areas of study namely evolution and classification are interlinked "Justify the statement ?

Answer»

Solution :a) Different forms of organisms or life have evolved during the course of evolution Classification DEALS with GROUPING of there organisms into group similarities and differences.
b) The characteristics commonly seen in any two species will be CLOSELY related and they will be closely related and they will have a more recent or common ancetor.
c) Thus, classification helps tracing the EVOLUTIONARY relationship between the two organisms. Hence it can be SAID that classification and evolution are interlinked.
Discussion
146.

Sky appears light blue on account of the phenomenon of___________ .

Answer»

SOLUTION :SCATTERING of LIGHT.
Discussion
147.

A student obtained a clear image of window grills on the screen . But the teacher told him to get the image of a tree far away, instead of the window . To get a clear image, the lens must be ……………. .

Answer»

away from the screen
behind the screen
TOWARDS the screen
at a very long DISTANCE from the screen

ANSWER :C
Discussion
148.

Parapodia : Annelida : : Tube feet : ……

Answer»

SOLUTION :ECHINODERMATA
Discussion
149.

Explain asexual reproduction in plants.

Answer»

Solution :(1) Vegetative propagation is the method of asexual reproduction in plants.
(2) It takes place with the help of vegetative partsof vegetative parts and bud.
(3) CARROT , beetroot and RADISH are the modified roots that perform vegetative propagation.

( 4) Potato, suran (Amorphophallus) and other tubes PROPAGATE with the help of 'eyes' which are buds. These eyes are PRESENT on the stem tubers.
(5) In case of plants like sugarcane and grasses, buds present on nodes perform vegetative propagation.
(6) Plants like Bryophyllum perform vegetative propagation with the help of buds present on leaf margin.
Discussion
150.

How can three resistors of resistances 2 Omega,3 Omega and 6 Omega be connected to give a total resistance of (a) 4 Omega (b) 1 Omega?

Answer»

SOLUTION :a) If we connect RESISTANCES of `3 Omega and 6 Omega` in parallel and then RESISTANCE of `2 Omega` is connected in series of the combination, the total resistance of combination is `4 Omega` as shown in fig.12.3(a) The combined resistance R. on the parallel grouping of `3 Omega and 6 Omega` resistances is given as:
`1/R.=1/3+1/6=(2+1)/6=3/6=1/2`
`implies R=2 Omega`
and total resistance of ENTIRE combination `R=2 Omega +R.=2+2=4 Omega`
(b) IF all the three resistances are joined in parallel as shown in fig.12.3(b) we have
`1/R=1/2+1/3+1/6=(3+2+1)/6=6/6=1/1 implies R=1 Omega`
Discussion