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InterviewSolution
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.
| 4951. |
If the current through the straight conductor is increased, the intensity of the magnetic field ............ |
| Answer» SOLUTION :INCREASES | |
| 4952. |
The refractive of three media are given below :{:("Medium",A,B,C),("Refractive index",1.65,1.71,1.47):}A light ray travels from medium A to medium B and another light ray travels from medium B to medium C. In which case does (a) the refracted ray bend towards the normal(b) the speed of light will be more. |
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Answer» Solution :(a) The refracted ray bend towards the normal when the light ray travels from MEDIUM A(rarer) to medium B (denser). (b) Speed of light is more in a OPTICALLY rarer medium i.e., a medium with the lowest value of refractive index. In this case it is medium C. |
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| 4953. |
If 80 g steam of temperature 97^@ Cis released on an ice slab of temperature 0^@C how much ice will melt? How much energy will be transferred to the ice when the stam will be transformed to water ? (Given : Latent heat of melting the ice ) L_("melt")=80 cal//g Latent heat of vaporiasation of water =L_("vap")=540 cal // g ) |
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Answer» Change is temperature `(DeltaT)` `=97-0=97^@C` We KNOW that: Latent heat of melting of ice `=L_("melt")=80 cal // g ` Latent heat of vaporisation of water `=L_("vap")=540 cal//g ` Specific heat of water `c_w = 1cal//g^@C` To find : i.Energy transferred (Q). iiMass of ice that melts (mi) FORMULAE: i . Heat released during conversion of steam into water at `97^@C(Q_1)= m_s xx L_(vap)` ii. Heat released during decrease of temperature of water from `97 ""^@C" "" to " " 0 "" "^@C " " (Q_2)` `=m_sxx c_s xx Delta T ` iii.Heat gained by ice (Q)`= m_i xx L_("melt")` Calculation From formula (i), `Q_1=80 xx 540 cal` From formula (ii) `Q_2= 80 xx 1 xx (97-0)` `= 80 xx 97 cal` According to princple of heat exchange , Total heat gained by ice `Q=Q_1+Q_2` `= 80 xx 540 +80xx 97` `=80 xx (540+97)` `= 80 xx 637` = 50960 cal This energy would cause `m_i` mass of ice to melt . From formula (iii), `therefore "" m_i xx L_("melt") = 50960` `therefore ""m_i =(50960)/(80) ` `=(80 xx 637)/(80)` `=637 g ` |
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| 4954. |
Electric field intensity (E) due to an electric dipole varies with distance (r) from the point of the center of dipole as : |
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Answer» `E prop (1)/(r)` |
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| 4955. |
An electric iron of power 2 kW is used for 3 hours. At Rs 5 per unit, the electricity bill will be .......... |
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Answer» Rs 45 `W = P xx t` = 2 KW `xx` 3 H = 6 kWh = 6 unit `:.` Cost of electric power consumed (electricity bill) `5 xx 6 = Rs 30` |
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| 4956. |
Statetwo serioushazards of electricity . |
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Answer» Solution :(1) If aperson accidently touches the live wire , he gets a severe shockwhichmayprove fatal . (2) Short - circuiting or overloadingcancause a spark WHICHMAY lead to FIRE in a a building . |
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| 4957. |
State whether the following statement is true or false : Rabbit has eyes which look sideways. |
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| 4958. |
Energy obtained from fossil fuels is green energy. True/False |
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Answer» Solution :(1) Fossil fuels like PETROL, diesel or natural gas when burnt, emit toxic GASES and soot particles. Thus, fossil fuels cause air pollution. (2) Burning of fossil fuels cause increased levels of carbon dioxide, carbon monoxide and nitrogen dioxide. (3) The increased carbon dioxide emission results in global warming. (4) Nitrogen oxide results LATER in acid-rain. Soot particles generated through burning of fuels cause respiratory problems like asthma. (5) Moreover, the fossil fuels are non-renewable and exhaustible.They haveto be EXPLORED from the deeper layers of the earth causing lots of environmental problems. Thus, ENERGY obtained from fossil fuels is not at all green energy. |
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| 4959. |
What part of the eye can be donated after death ? |
| Answer» Solution :One can live in the eyes of others after his death. The CORNEA from dead body is removed within 6 HOURS of the death and TRANSPLANTED in the eyes of blind PERSON with opaque cornea. His opaque cornea is replaced by transparent cornea of dead person. | |
| 4960. |
What are the functions of live and neutral wires ? |
| Answer» Solution :The live wire brings in the CURRENT while the neutral wire PROVIDES the RETURN path for the current. | |
| 4961. |
"_________________" is a word's largest organization engaged in environment activities. |
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Answer» WWF |
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| 4962. |
Herdmaniahas notochord in only tail region and hence it is called Urochordate. |
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| 4963. |
Local people have a major stake in forest resources. IIIusttrate giving four examples how conservation of forests is essential for the existence of their life. |
| Answer» Solution :Involvement of local people in the protection/conservation of forests as well as avoiding the exhaustion of the FOREST resources which FULFILL the varied needs of local people. Such as -(i) Large quantity of firewood, small timber and thatch, (ii) Bamboo to MAKE slats for huts and baskets, (III) Wood for making implements for agriculture, hunting and fishing and (IV) Leaves for fodder, etc. | |
| 4964. |
Why does a compass needle show deflection when brought near a current carrying conductor ? |
| Answer» Solution :DUE to production of MAGNETIC FIELD around the current carrying CONDUCTOR. | |
| 4965. |
A current of 200 mA flows through a 4 kOhm resistor. What is the potential difference across the resistor? |
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Answer» Solution :The POTENTIAL DIFFERENCE across the resistor `V =IR` `= 200 xx10^(-3) xx4 XX 10^3` `=800 V` |
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| 4966. |
Heat energy is being produced in a resistance in a circuit at the rate of 100 W. The current of 3 A is flowing in the circuit. What must be the value of the resistance ? |
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Answer» `"To find:RESISTANCE (R)"` `"Formulae:i.P VIii.V = IR"` `"Calculation:From FORMULA (i),"` `V=(P)/(I)=(100)/(3)=33.3V` From formula (ii), `R=(V)/(I)=(33.3)/(3)~~11Omega` |
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| 4967. |
Describe the areas where acid rains are most likely expected. |
| Answer» Solution :Acid RAINS are most likely EXPECTED in industrial AREAS where there is emission of oxides of nitrogen and sulphur. | |
| 4968. |
Consider a circular loop of wirelying in the planeof the table . Letthe currentpass through the loop clockwise . Apply the Right-hand thumb ruleto findout the direction of the magnetic field inside and outside the loop. |
Answer» Solution :Using the RIGHT - handthumb rule, the directionof the magnetic FIELD insdieand outsidethe cirularloopof wirecarrying anelectric currentcan be found. THISIS shown in thefollowingfigure .  Thedotted magnetic field lines are perpendicularto theplaneof the PAPER . The front faceof the loop behaveas the south pole and theback face , i.e., the facetouchingthe plane of thetablebehaves as the NORTH pole . |
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| 4969. |
The amount of scattering of light is inversely proportional to the ________ power of its wavelength. |
| Answer» SOLUTION :INVERSELY | |
| 4970. |
State one function of iris in human eye. |
| Answer» SOLUTION :Function of Iris : It CONTROLS the size of the PUPIL. | |
| 4971. |
What will be the colour of the sky when it is observed from a place in the absence of any atmosphere? |
| Answer» SOLUTION :BLACK (DARK). | |
| 4972. |
Which of the following is not an example of a bio-mass energy source? |
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Answer» WOOD |
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| 4973. |
Draw a V- I graph. |
Answer» SOLUTION :
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| 4976. |
If momentum (p), area (A) and time(t) are taken to be fundamental quantities then energy has the dimensional formula |
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Answer» `[PA^(1//2)T^(-1)]` `=("CHANGE in momentum")/("TIME")xxsqrt("area")=[pA^(1//2)A^(-1)]` |
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| 4977. |
The sun near the horizon appears flattened at sunset and sunrise. Explain why. |
| Answer» Solution :At sunrise and sunset, the rays from the SUN travel a larger distance in the earth.s atmosphere to REACH the eyes of the observer. Due to a decrease in density and refractive INDEX in the atmosphere, with increasing altitude these rays undergo refraction [atmospheric refractio]. So, the rays from the top and bottom portion of the sun NEAR the horizon are refracted by different degrees. But the rays from the middle portion of the sun are refracted by the same amount. This causes theapparent flattering the sun.s disc at the top and bottom but it remains CURVED at the middle. | |
| 4978. |
Number of molecules N in a gas is equal to the product of number of mole (in) of gas and Avogadro's number (N_(A)) |
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| 4979. |
(a) Draw a labelled diagram to show the domestic electric wiring from an electric pole to a room. Give the wiring for a bulb and a three-pin socket only. (b) State two hazards associated with the use of electricity. (c) State the important precautions which should be observed in the use of electricity. (d) What will you do if you see a person coming in contact with a live wire ? (e) Explain why, electric switches should not be operated with wet hands. |
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| 4980. |
The path of a ray light coming from air passing through a rectangular glass slab traced by four students are shown as A, B, C and D in Figure. Which one of them is correct ? |
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Answer» A |
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| 4981. |
What is the current in a circuit if the charge passing through each point is 20 C in 40 s? |
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Answer» SOLUTION :Given, Charge = Q = 20 C, Time = t = 40 SEC As we know that current is the RATE of flow of charge or by ohm.s law we can say Charge [Q] = current [I] `xx` time [t] `I=Q/trArrI=20/40=1/2amp.=0.5amp.` |
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| 4982. |
Define electrical resistivity. |
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Answer» Solution :(i) The electrical RESISTIVITY of a material is DEFINED as the resistance of a conductor ofunit LENGTH and UNIT area of cross section. (ii) Its unit is OHM metre. |
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| 4983. |
Analyse the following observation table showing variation of image-distance (v) with object-distance (u) in case of a convex lens and answer the questions that follow without doing any calculations : {:("S.No.","Object-distance","Image-distance"),(,"u (cm)","v (cm)"),(1,-100,+25),(2,-60,+30),(3,-40,+40),(4,-30,+60),(5,-25,+100),(6,-15,+ 120):} (a) What is the focal length of the convex lens ? Give reason to justify your answer. (b) Write the seril number of the observation which is not correct. On what basis have you arrived at this conclusion ? (c) Select an appropriate scale and draw a ray diagram for the observation at S.NO. 2. Also find the approximate value of magnification. |
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Answer» Solution :(a) We know that if an object is placed at 2F on one side of convex lens then its real image is formed on other side of lens at 2F. Hence as per observaton at S.No. 3, we conclude that 2F POINT is situated at 40 cm. Thus, 2f = 40 cm and hence f = 20 cm. (b) The OBSERVATION at S.No. 6 is WRONG because for an object situated between optical centre and focus point F (that is `|u| lt f`) the image is a virtual image and is formed on same side of lens. Thus, for u = - 15 cm, sign of V must be -ve and VALUE of v cannot be + 120 cm. (c) The ray diagram is given in Figure Magnification of image `m = (v)/(u) = ((+30))/((-60)) = - 0.5` 
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| 4984. |
Find the effecitve resistance between A and B in the give circuit. |
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Answer» <P> Solution :EFFECTIVE resistance in parallel combination `3Omega` and `2Omega``(1)/(R_(p))=(1)/(R_(1))+(1)/(R_(2))=1/3+1/2=(2+3)/(6)=(5)/(6)Omega` `:.R_(p)=(6)/(5)1.2Omega` Effective resistance in series combination `1.2Omega` and `2Omega` `R_(S)=R_(1)+R_(2)=1.2+2=3.2Omega` 
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| 4985. |
The combustible substances formed from the dead remains of the animals and plants which were buried under the surface of eart are called |
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| 4986. |
The point on the principal axis of a lens such that a ray of light passing through it, emerges undeviated |
| Answer» SOLUTION :OPTICAL CENTRE | |
| 4987. |
What is meant by isomerism ? Why do first three members of the alkane series not show isomerism ? Write the structure of two isomers of the fourth member of this series. |
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Answer» Solution :ISOMERISM is the EXISTENCE of two or more compounds having same MOLECULAR formula but different structures. It is not possible for them to have different structures/only one structure is possible for each of them. Structures: `CH_(3)-CH_(2)-CH_(2)-CH_(3),""CH_(3)-underset(CH_(3))underset(|)"CH"-CH_(3)` |
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| 4988. |
Heat given (H) to a substance was plotted against rise in temperature (theta). Which of the following parts of the graph (Fig. 6.3), most correctly depicts the latent heat of the substance? |
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Answer» AB |
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| 4991. |
Two forces each of magnitude 2N act vertically upwards and downwards respectively at the two ends of a uniform rod of length 1m which is pivoted at its centre. Draw a diagram of the arrangement and determine the resultant moment of forces about the mid point of the rod. |
Answer» Solution :The arrangement is shown in fig.1.21 GIVEN below . AB is the ROD which is pivoted at its centre O.  Given `AB=1m therefore OA=OB=0.5m` Moment of force F (=2N) at A about the POINT O `=F TIMES OA =2 times 0.5 =1.0 Nm` (clockwise) Moment of force F (=2N) at B about the point O `=F times OB=2 times 0.5=1.0 Nm` (clockwise) `therefore` TOTAL moment of forces about the mid point O `=1.0+1.0=2.0 N m` (clockwise) |
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| 4992. |
Which is not a homopolymer :- |
Answer» SOLUTION :The polymers FORMED by REPETITION of single MONOMER are called homopolymer . E.g. polyethylene 
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| 4993. |
At what place of the magnetare the magneticfieldlines closer ? |
| Answer» SOLUTION :NEARTHE POLESOF THEMAGNET . | |
| 4994. |
Geographical and reproductive isolation of organisms gradually leads to speciation. This statement is based on the concept of speciation. |
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Answer» Solution :(1) Every species SURVIVES in SPECIFIC geographical conditons. The requirements of food and habitat is specific for each species. Their reproductive ability and period is also different. (2) Therefore, the individuals from one species cannot reproduce with individuals from other species. (3) When they are SEPARATED by a distance or geographical barriers they are said to be isolated geographically. (4) When they cannot reproduce with each other, they are said to be isolated reproductively. (5) The ancestor species of both these subspecies may be the same but DUE to isolation over a very long-time duration, there is genetic variation between the two. Therefore, the isolation leads to speciation. |
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| 4995. |
State ohm's law. How can it verified experimentally? Does it hold good in all conditions? Comment. |
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Answer» Solution :For statement of Ohm.s law see point Number 13 under the heading" Chapter At A Glance" The circuit diagram of the experimental set up has been shown in Fig.12.23. Here ,XY is a resistance wire,an ammeter and V a voltmeter. A battery of four cells is being used as a current source and K is a PLUG key. Initially use one cell only. Put plug in key K and note current and voltage by noting ammeter and voltmeter readings respectively. Let these to be `l_1 and V_1`. Then connect two cells in the circuit and note current `l_2 ` and potential difference `V_2` across the resistances. Similarly take readings with THREE cells and four cells in the circuit. From our observations, we find that `V_1/I_1=V_2/I_2=V_3/I_3=V_4/I_4=a` constant =R IF we plot V-I graph the graph comes out to be a straight line as shown in fig.12.24. It experimentally VERIFIES Ohm.s law. Ohm.s law does not hold good under all conditions. It is true for metals and alloys only provided that temperature does not CHANGE during the course of experiment. 
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| 4996. |
One word is incorrect in the statement . Change it to make the statement correct : Arthropoda animals bear numerous pores on their body . |
| Answer» SOLUTION :Porifera ANIMALS BEAR numerous PORES on their body . | |
| 4997. |
A person with a myopic eye cannot see clearly the objects placed beyond 1.5 m. Mention two possible reasons due to which this defect may arise. With the help of ray diagrams show: (a) Why is he unable to see clearly the objects placed beyond 1.5 m from his eye, and (b) What should be the type of the corrective lens used to restore proper vision and how this effect is corrected by the use of this lens? |
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Answer» Solution :(a) (i) EXCESSIVE curvature of EYE lens, (II) Elongation of eye ball (B) Concave lens. |
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| 4998. |
For a given voltage V, if resistance is changed from R to (R/n) power consumed changes from P to |
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Answer» `NP` Rate occonsumption whenused at `200 V =( (200)^2 xx60 W )/( (200)^2) LT 60` |
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| 4999. |
How is zinc extracted from its ore zinc sulphide or zinc carbonate ? |
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Answer» Solution :The crude ZINC sulphide ore is heated stronglyin excess of air. Zinc sulphide is converted into zinc oxide. This process is known as roasting . `underset("Zinc sulphide")(2ZnS_((s))) + 3O_(2(G)) to underset(" zinc oxide")( 2ZnO_((s))) + underset(" Sulphur dioxide ") (2SO_(2(g)))` The crude zinc carbonate ore is heated STRONGLY in limitedsupply of air. Zinc carbonte is converted into zincoxide. Thisprocess is known as calcination . ` underset(" Zinc carbonate") (ZnCO_(3(s))) to underset("Zinc oxide")(ZnO_(s)) + (" Sulphur dioxide")(CO_(2(g)))` The zinc oxide is reduced to zinc by usinga reducingagentsuchs carbon ` underset(" Zinc oxide " ) (ZnO_((s))) + underset( "Carbon") C_((s)) to Zn_((s)) + underset("Carbon monoxide")(CO_((g)))` |
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| 5000. |
Draw a labelled diagramm of an electric motor. Explain its principle and working. What is the function of a split ring in an electric motor ? |
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Answer» <P> Solution : Principle of Electric Motor : A current-carrying conductor, when placed in a magnetic FIELD, experiences a force. If the direction of the field and that of the current are mutually PERPENDICULAR then force acting on the conductor will be perpendicular to both and will be given by Fleming.s left-hand rule. Due to this force the conductor begins to move. Working of Electric Motor: Current in the coil ABCD enters form the source battery through conducting brush X and flows back to the battery through brush Y. The current in arm AB of the coil flows form A to B. In arm CD it flows from C to D, that is, opposite to the direction of current through arm AB. We find that the force acting on arm AB pushes it downwards while the force acting on arm CD pushes it upwards. Thus the coil and the axle O, mounted FREE turn about an axis, rotate anti- clockwise. At half rotation, Q makes contact with the brush X and P with brush Y. Therefore the current in the coil gets REVERSED and flows along the path DCBA. The reversal of current also revcrses the direction of force acting on the two arms AB and CD. Thus the arm AB of the coil that was earlier pushed down is now pushed up and the arm CD previously pushed up is now pushed down. Therefore the coil and the axle rotate half a turn more in the same direction. The reversing of the current is repeated at each half rotation, giving rise to a continuous rotation of the coil and to the axle. Role of split ring : To change the direction of current flowing through the col after each halt- rotation. |
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