MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 3651. |
In a mean life of a radioactive sample [MP PMT 2000, 03] |
| A. | About 1/3 of substance disintegrates |
| B. | About 2/3 of the substance disintegrates |
| C. | About 90% of the substance disintegrates |
| D. | Almost all the substance disintegrates |
| Answer» C. About 90% of the substance disintegrates | |
| 3652. |
In the given reaction\[_{z}{{X}^{A}}{{\to }_{z+1}}{{Y}^{A}}{{\to }_{z-1}}{{K}^{A-4}}{{\to }_{z-1}}{{K}^{A-4}}\]Radioactive radiations are emitted in the sequence [AIIMS 1982; CBSE PMT 1993; AFMC 1999; MP PET 2002] |
| A. | \[\frac{2{{\varepsilon }_{0}}hc}{{{e}^{2}}}\] |
| B. | \[\beta ,\ \alpha ,\ \gamma \] |
| C. | \[\gamma ,\ \alpha ,\ \beta \] |
| D. | \[\beta ,\ \gamma ,\ \alpha \] |
| Answer» C. \[\gamma ,\ \alpha ,\ \beta \] | |
| 3653. |
The activity of a radioactive sample is 1.6 curie and its half-life is 2.5 days. Its activity after 10 days will be [MP PMT 2000] |
| A. | 0.8 curie |
| B. | 0.4 curie |
| C. | 0.1 curie |
| D. | 0.16 curie |
| Answer» D. 0.16 curie | |
| 3654. |
What fraction of a radioactive material will get disintegrated in a period of two half-lives [MP PET 2000] |
| A. | Whole |
| B. | Half |
| C. | One-fourth |
| D. | Three-fourth |
| Answer» E. | |
| 3655. |
A nucleus \[_{Z}^{A}X\] emits an a-particle. The resultant nucleus emits a \[{{\beta }^{+}}\]particle. The respective atomic and mass no. of the final nucleus will be [MP PET 2000] |
| A. | Z ? 3, A ? 4 |
| B. | Z ? 1, A ? 4 |
| C. | Z ? 2, A ? 4 |
| D. | Z, A ? 2 |
| Answer» B. Z ? 1, A ? 4 | |
| 3656. |
Which is the correct expression for half-life [CBSE PMT 2000] |
| A. | \[{{(t)}_{1/2}}=\log 2\] |
| B. | \[{{(t)}_{1/2}}=\frac{\lambda }{\log 2}\] |
| C. | \[{{(t)}_{1/2}}=\frac{\lambda }{\log \,\text{2}}(2.303)\] |
| D. | \[{{(t)}_{1/2}}=\frac{2.303\text{ log 2}}{\lambda }\] |
| Answer» E. | |
| 3657. |
If half-life of a substance is 3.8 days and its quantity is 10.38 gm. Then substance quantity remaining left after 19 days will be [RPMT 2000; AFMC 2002] |
| A. | 0.151 gm |
| B. | 0.32 gm |
| C. | 1.51 gm |
| D. | 0.16 gm |
| Answer» C. 1.51 gm | |
| 3658. |
After five half lives what will be the fraction of initial substance [RPMT 2000] |
| A. | \[{{\left( \frac{1}{2} \right)}^{10}}\] |
| B. | \[{{\left( \frac{1}{2} \right)}^{5}}\] |
| C. | \[{{\left( \frac{1}{2} \right)}^{4}}\] |
| D. | \[{{\left( \frac{1}{2} \right)}^{3}}\] |
| Answer» C. \[{{\left( \frac{1}{2} \right)}^{4}}\] | |
| 3659. |
The activity of a radioactive sample [BHU 2000] |
| A. | Can be increased by heating it |
| B. | Is independent of physical parameter |
| C. | Cannot be increased by any method |
| D. | Both (b) and (c) |
| Answer» E. | |
| 3660. |
A radioactive substance has a half-life of 1 year. The fraction of this material, that would remain after 5 years will be [CPMT 2000] |
| A. | \[\frac{1}{32}\] |
| B. | \[\frac{1}{5}\] |
| C. | \[\frac{1}{2}\] |
| D. | \[\frac{4}{5}\] |
| Answer» B. \[\frac{1}{5}\] | |
| 3661. |
In beta decay [UPSEAT 2000; MP PMT 2000] |
| A. | The parent and daughter nuclei have same number of protons |
| B. | The daughter nucleus has one proton less than the parent nucleus |
| C. | The daughter nucleus has one proton more than the parent nucleus |
| D. | The daughter nucleus has one neutron more than the parent nucleus |
| Answer» D. The daughter nucleus has one neutron more than the parent nucleus | |
| 3662. |
Alpha rays emitted from a radioactive substance are [CBSE PMT 1999; RPET 2000] |
| A. | Negatively charged particles |
| B. | Ionised hydrogen nuclei |
| C. | Doubly ionised helium atom |
| D. | Uncharged particles having the mass equal to proton |
| Answer» D. Uncharged particles having the mass equal to proton | |
| 3663. |
Radioactive substance do not emit [CPMT 1997; AIEEE 2003] |
| A. | Electron |
| B. | Helium nucleus |
| C. | Positron |
| D. | Proton |
| Answer» B. Helium nucleus | |
| 3664. |
Two stars emit maximum radiation at wavelength 3600\[{AA}\] and 4800\[{AA}\] respectively. The ratio of their temperatures is [MP PMT 1991] |
| A. | 1 : 2 |
| B. | 0.127777777777778 |
| C. | 4 : 3 |
| D. | 0.0840277777777778 |
| Answer» D. 0.0840277777777778 | |
| 3665. |
The wavelength of maximum emitted energy of a body at 700 K is 4.08 \[\mu m\]. If the temperature of the body is raised to 1400 K, the wavelength of maximum emitted energy will be [MP PET 1990] |
| A. | \[1.02\ \mu m\] |
| B. | 16.32\[\mu m\] |
| C. | 8.16\[\mu m\] |
| D. | 2.04\[\mu m\] |
| Answer» E. | |
| 3666. |
A black body at 200 K is found to exit maximum energy at a wavelength of \[14\mu m\]. When its temperature is raised to 1000K, the wavelength at which maximum energy is emitted is [RPMT 1998; MP PET 1991; BVP 2003] |
| A. | \[14\mu m\] |
| B. | \[70\mu F\] |
| C. | \[2.8\mu m\] |
| D. | \[2.8mm\] |
| Answer» D. \[2.8mm\] | |
| 3667. |
If black wire of platinum is heated, then its colour first appear red, then yellow and finally white. It can be understood on the basis of [MP PMT 1984] |
| A. | Wien's displacement law |
| B. | Prevost theory of heat exchange |
| C. | Newton's law of cooling |
| D. | None of the above |
| Answer» B. Prevost theory of heat exchange | |
| 3668. |
Colour of shining bright star is an indication of its [AIIMS 2001; RPMT 1999; BCECE 2005] |
| A. | Distance from the earth |
| B. | Size |
| C. | Temperature |
| D. | Mass |
| Answer» D. Mass | |
| 3669. |
If wavelengths of maximum intensity of radiations emitted by the sun and the moon are \[0.5\times {{10}^{-6}}m\] and \[{{10}^{-4}}m\] respectively, the ratio of their temperatures is [MP PMT 1990] |
| A. | 1/100 |
| B. | 1/200 |
| C. | 100 |
| D. | 200 |
| Answer» E. | |
| 3670. |
The intensity of radiation emitted by the sun has its maximum value at a wavelength of \[510\ nm\] and that emitted by the north star has the maximum value at \[350\ nm\]. If these stars behave like black bodies, then the ratio of the surface temperature of the sun and north star is [IIT 1997 Cancelled; JIPMER 2000; AIIMS 2000] |
| A. | 1.46 |
| B. | 0.69 |
| C. | 1.21 |
| D. | 0.83 |
| Answer» C. 1.21 | |
| 3671. |
The wavelength of radiation emitted by a body depends upon [MP PMT 1992] |
| A. | The nature of its surface |
| B. | The area of its surface |
| C. | The temperature of its surface |
| D. | All the above factors |
| Answer» D. All the above factors | |
| 3672. |
The maximum energy in thermal radiation from a source occurs at the wavelength 4000Å. The effective temperature of the source is [AMU (Engg.) 1999] |
| A. | \[7325\,K\] |
| B. | \[80000K\] |
| C. | \[{{10}^{4}}\,K\] |
| D. | \[{{10}^{6}}\,K\] |
| Answer» B. \[80000K\] | |
| 3673. |
A particular star (assuming it as a black body) has a surface temperature of about \[5\times {{10}^{4}}K.\]The wavelength in nanometers at which its radiation becomes maximum is (b = 0.0029 mK) [EAMCET (Med.) 2003] |
| A. | 48 |
| B. | 58 |
| C. | 60 |
| D. | 70 |
| Answer» C. 60 | |
| 3674. |
The absolute temperatures of two black bodies are 2000 K and 3000 K respectively. The ratio of wavelengths corresponding to maximum emission of radiation by them will be [RPMT 2003] |
| A. | 2 : 3 |
| B. | 3 : 2 |
| C. | 9 : 4 |
| D. | 4 : 9 |
| Answer» C. 9 : 4 | |
| 3675. |
The temperature of sun is 5500 K and it emits maximum intensity radiation in the yellow region \[(5.5\times {{10}^{-7}}m)\]. The maximum radiation from a furnace occurs at wavelength \[11\times {{10}^{-7}}m.\]The temperature of furnace is [J & K CET 2000] |
| A. | 1125 K |
| B. | 2750 K |
| C. | 5500 K |
| D. | 11000 K |
| Answer» C. 5500 K | |
| 3676. |
The radiation energy density per unit wavelength at a temperature T has a maximum at a wavelength l0. At temperature \[2T\], it will have a maximum at a wavelength [UPSEAT 2004] |
| A. | 4l0 |
| B. | 2l0 |
| C. | l0/2 |
| D. | l0/4 |
| Answer» D. l0/4 | |
| 3677. |
What will be the ratio of temperatures of sun and moon if the wavelengths of their maximum emission radiations rates are 140 Å and 4200 Å respectively [J & K CET 2004] |
| A. | 1 : 30 |
| B. | 30 : 1 |
| C. | 42 : 14 |
| D. | 14 : 42 |
| Answer» C. 42 : 14 | |
| 3678. |
Solar radiation emitted by sun resembles that emitted by a black body at a temperature of 6000 K. Maximum intensity is emitted at a wavelength of about 4800Å. If the sun were to cool down from 6000 K to 3000 K then the peak intensity would occur at a wavelength [UPSEAT 2002] |
| A. | 4800Å |
| B. | 9600Å |
| C. | 7200Å |
| D. | 6400Å |
| Answer» C. 7200Å | |
| 3679. |
The maximum wavelength of radiations emitted at 900 K is \[4\mu m\]. What will be the maximum wavelength of radiations emitted at 1200 K [BHU 2002] |
| A. | \[3\mu m\] |
| B. | \[0.3\mu m\] |
| C. | \[1\mu m\] |
| D. | \[1\,\,m\] |
| Answer» B. \[0.3\mu m\] | |
| 3680. |
Relation between the colour and the temperature of a star is given by [Kerala PET 2001] |
| A. | Wein?s displacement law |
| B. | Planck?s law |
| C. | Hubble?s law |
| D. | Fraunhofer diffraction law |
| Answer» B. Planck?s law | |
| 3681. |
A black body at a temperature of 1640 K has the wavelength corresponding to maximum emission equal to 1.75\[\mu \]. Assuming the moon to be a perfectly black body, the temperature of the moon, if the wavelength corresponding to maximum emission is 14.35 m is [Kerala (Med.) 2002] |
| A. | 100 K |
| B. | 150 K |
| C. | 200 K |
| D. | 250 K |
| Answer» D. 250 K | |
| 3682. |
A black body has maximum wavelength \[{{\lambda }_{m}}\] at temperature 2000 K. Its corresponding wavelength at temperature 3000 K will be [CBSE PMT 2001; Kerala PET 2005] |
| A. | \[\frac{3}{2}{{\lambda }_{m}}\] |
| B. | \[\frac{2}{3}{{\lambda }_{m}}\] |
| C. | \[\frac{4}{9}{{\lambda }_{m}}\] |
| D. | \[\frac{9}{4}{{\lambda }_{m}}\] |
| Answer» C. \[\frac{4}{9}{{\lambda }_{m}}\] | |
| 3683. |
On increasing the temperature of a substance gradually, which of the following colours will be noticed by you [Pb. PMT 1995; Pb. PET 1996; CPMT 1995, 98; KCET 2000] |
| A. | White |
| B. | Yellow |
| C. | Green |
| D. | Red |
| Answer» B. Yellow | |
| 3684. |
How is the temperature of stars determined by [BHU 1999, 02; DCE 2000, 03] |
| A. | Stefan?s law |
| B. | Wein?s displacement law |
| C. | Kirchhoff?s law |
| D. | Ohm?s law |
| Answer» C. Kirchhoff?s law | |
| 3685. |
The maximum wavelength of radiation emitted at \[2000\ K\]is \[4\mu m\]. What will be the maximum wavelength of radiation emitted at [MP PMT/PET 1998; DPMT 2000] |
| A. | \[3.33\ \mu m\] |
| B. | \[0.66\ \mu m\] |
| C. | \[1\ \mu m\] |
| D. | \[1\ m\] |
| Answer» B. \[0.66\ \mu m\] | |
| 3686. |
The wavelength of maximum energy released during an atomic explosion was \[2.93\times {{10}^{-10}}m\]. Given that Wein's constant is \[2.93\times {{10}^{-3}}m-K\], the maximum temperature attained must be of the order of [Haryana CEE 1996; MH CET 2002; Pb. PET 2000] |
| A. | \[{{10}^{-7}}K\] |
| B. | \[{{10}^{7}}K\] |
| C. | \[{{10}^{-13}}K\] |
| D. | \[5.86\times {{10}^{7}}K\] |
| Answer» C. \[{{10}^{-13}}K\] | |
| 3687. |
The maximum energy in the thermal radiation from a hot source occurs at a wavelength of \[11\times {{10}^{-5}}cm\]. According to Wein's law, the temperature of the source (on Kelvin scale) will be \[n\] times the temperature of another source (on Kelvin scale) for which the wavelength at maximum energy is \[5.5\times {{10}^{-5}}cm\]. The value \[n\] is [CPMT 1991] |
| A. | 2 |
| B. | 4 |
| C. | \[\frac{1}{2}\] |
| D. | 1 |
| Answer» D. 1 | |
| 3688. |
If the temperature of the sun becomes twice its present temperature, then [MP PET 1989; RPMT 1996] |
| A. | Radiated energy would be predominantly in infrared |
| B. | Radiated energy would be predominantly in ultraviolet |
| C. | Radiated energy would be predominantly in X-ray region |
| D. | Radiated energy would become twice the present radiated energy |
| Answer» C. Radiated energy would be predominantly in X-ray region | |
| 3689. |
If a black body is heated at a high temperature, it seems to be [DPMT 2001] |
| A. | Blue |
| B. | White |
| C. | Red |
| D. | Black |
| Answer» C. Red | |
| 3690. |
Four pieces of iron heated in a furnace to different temperatures show different colours listed below. Which one has the highest temperature [MP PET 1992] |
| A. | White |
| B. | Yellow |
| C. | Orange |
| D. | Red |
| Answer» B. Yellow | |
| 3691. |
A black body emits radiations of maximum intensity at a wavelength of \[5000{AA}\], when the temperature of the body is \[{{1227}^{o}}C\]. If the temperature of the body is increased by \[{{1000}^{o}}C\], the maximum intensity of emitted radiation would be observed at [MP PET 1992] |
| A. | \[2754.8{AA}\] |
| B. | \[3000{AA}\] |
| C. | \[3500{AA}\] |
| D. | \[4000{AA}\] |
| Answer» C. \[3500{AA}\] | |
| 3692. |
According to Wein's law [DCE 1995, 96; MP PET/PMT 1988 DPMT 1999; AIIMS 2002; CBSE PMT 2004] |
| A. | \[{{\lambda }_{m}}T\]= constant |
| B. | \[\frac{{{\lambda }_{m}}}{T}\]= constant |
| C. | \[\frac{T}{{{\lambda }_{m}}}\]= constant |
| D. | \[T+{{\lambda }_{m}}\]= constant |
| Answer» B. \[\frac{{{\lambda }_{m}}}{T}\]= constant | |
| 3693. |
If temperature of a black body increases from \[{{7}^{o}}C\] to \[{{287}^{o}}C\], then the rate of energy radiation increases by [AIIMS 1997; Haryana PMT 2000; RPMT 2003] |
| A. | \[{{\left( \frac{287}{7} \right)}^{4}}\] |
| B. | 16 |
| C. | 4 |
| D. | 2 |
| Answer» C. 4 | |
| 3694. |
In MKS system, Stefan's constant is denoted by \[\sigma \]. In CGS system multiplying factor of \[\sigma \]will be |
| A. | 1 |
| B. | \[{{10}^{3}}\] |
| C. | \[{{10}^{5}}\] |
| D. | \[{{10}^{2}}\] |
| Answer» C. \[{{10}^{5}}\] | |
| 3695. |
Energy is being emitted from the surface of a black body at \[{{127}^{o}}C\] temperature at the rate of \[1.0\times {{10}^{6}}J/\sec -{{m}^{2}}\]. Temperature of the black body at which the rate of energy emission is \[16.0\times {{10}^{6}}J/\sec -{{m}^{2}}\] will be [MP PMT 1991; AFMC 1998] |
| A. | \[{{254}^{o}}C\] |
| B. | \[{{508}^{o}}C\] |
| C. | \[{{527}^{o}}C\] |
| D. | \[{{727}^{o}}C\] |
| Answer» D. \[{{727}^{o}}C\] | |
| 3696. |
The spectral energy distribution of star is maximum at twice temperature as that of sun. The total energy radiated by star is [J & K CET 2005] |
| A. | Twice as that of the sun |
| B. | Same as that of the sun |
| C. | Sixteen times as that of the sun |
| D. | One sixteenth of sun |
| Answer» D. One sixteenth of sun | |
| 3697. |
When the body has the same temperature as that of surroundings [UPSEAT 1998; Orissa JEE 2004] |
| A. | It does not radiate heat |
| B. | It radiates the same quantity of heat as it absorbs |
| C. | It radiates less quantity of heat as it receives from surroundings |
| D. | It radiates more quantity of heat as it receives heat from surroundings |
| Answer» C. It radiates less quantity of heat as it receives from surroundings | |
| 3698. |
Two identical objects A and B are at temperatures TA and TB respectively. Both objects are placed in a room with perfectly absorbing walls maintained at temperatures T \[({{T}_{A}}>T>{{T}_{B}}).\] The objects A and B attain temperature T eventually which one of the following is correct statement [CPMT 1997] |
| A. | ?A? only emits radiations while B only absorbs them until both attain temperature |
| B. | A loses more radiations than it absorbs while B absorbs more radiations that it emits until temperature T is attained |
| C. | Both A and B only absorb radiations until they attain temperature T |
| D. | Both A and B only emit radiations until they attain temperature T |
| Answer» C. Both A and B only absorb radiations until they attain temperature T | |
| 3699. |
A black body of surface area 10cm2 is heated to 127°C and is suspended in a room at temperature 27°C. The initial rate of loss of heat from the body at the room temperature will be [Pb. PET 1997] |
| A. | 2.99 W |
| B. | 1.89 W |
| C. | 1.18 W |
| D. | 0.99 W |
| Answer» E. | |
| 3700. |
Rate of cooling at 600K, if surrounding temperature is 300K is R. The rate of cooling at 900K is [DPMT 2002] |
| A. | \[\frac{16}{3}R\] |
| B. | \[2R\] |
| C. | \[3R\] |
| D. | \[\frac{2}{3}R\] |
| Answer» B. \[2R\] | |