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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.
| 3551. |
The rate of disintegration of fixed quantity of a radioactive element can be increased by [MP PMT 1997, 2003] |
| A. | Increasing the temperature |
| B. | Increasing the pressure |
| C. | Chemical reaction |
| D. | It is not possible |
| Answer» E. | |
| 3552. |
In a radioactive decay, neither the atomic number nor the mass number changes. Which of the following would be emitted in the decay process [MP PET 1997] |
| A. | Proton |
| B. | Neutron |
| C. | Electron |
| D. | Photon |
| Answer» E. | |
| 3553. |
The relationship between \[\lambda \]and half life \[({{T}_{1/2}})\]of a radioactive substance is [RPMT 1996; MP PMT 1996] |
| A. | \[\lambda =\frac{{{\log }_{10}}2}{{{T}_{1/2}}}\] |
| B. | \[\lambda =\frac{{{\log }_{e}}2}{{{T}_{1/2}}}\] |
| C. | \[\lambda =\frac{{{\log }_{2}}10}{{{T}_{1/2}}}\] |
| D. | \[\lambda =\frac{{{\log }_{2}}e}{{{T}_{1/2}}}\] |
| Answer» C. \[\lambda =\frac{{{\log }_{2}}10}{{{T}_{1/2}}}\] | |
| 3554. |
The counting rate observed from a radioactive source at t=0 second was 1600 counts per second and at t=8 seconds it was 100 counts per second. The counting rate observed, as counts per second at t=6 seconds, will be [MP PET 1996; UPSEAT 2000; Pb. PET 2004; Kerala PET 2005] |
| A. | 400 |
| B. | 300 |
| C. | 200 |
| D. | 150 |
| Answer» D. 150 | |
| 3555. |
The radioactive nucleus \[_{7}{{N}^{13}}\]decays to \[_{6}{{C}^{13}}\] through the emission of [MP PET 1996] |
| A. | Neutron |
| B. | Proton |
| C. | Electron |
| D. | Positron |
| Answer» E. | |
| 3556. |
A radioactive nucleus \[_{92}{{X}^{235}}\]decays to \[_{91}{{Y}^{231}}\]. Which of the following particles are emitted [MP PMT 1995] |
| A. | One alpha and one electron |
| B. | Two deuterons and one positron |
| C. | One alpha and one proton |
| D. | One proton and four neutrons |
| Answer» B. Two deuterons and one positron | |
| 3557. |
N atoms of a radioactive element emit n alpha particles per second. The half life of the element is [MP PET 1995; MP PMT 1997, 2003] |
| A. | \[\frac{n}{N}\]sec |
| B. | \[\frac{N}{n}\] sec |
| C. | \[\frac{0.693\ N}{n}\] sec |
| D. | \[5,099\ c{{m}^{-1}}\] sec |
| Answer» D. \[5,099\ c{{m}^{-1}}\] sec | |
| 3558. |
A element used for radioactive carbon dating for more than 5600 years is [BHU 1995] |
| A. | \[C-14\] |
| B. | \[U-234\] |
| C. | \[U-238\] |
| D. | \[Po-94\] |
| Answer» B. \[U-234\] | |
| 3559. |
Some radioactive nucleus may emit [IIT 1986] |
| A. | Only one \[-13.6\ eV\] or \[\gamma \]at a time |
| B. | All the three \[_{92}{{U}^{238}}\] and \[\gamma \] one after another |
| C. | All the three \[\alpha ,\ \beta \] and \[\gamma \] simultaneously |
| D. | Only\[\alpha \] and \[\beta \] simultaneously |
| Answer» B. All the three \[_{92}{{U}^{238}}\] and \[\gamma \] one after another | |
| 3560. |
A radioactive substance has a half-life of 60 minutes. After 3 hours, the fraction of atom that have decayed would be [BHU 1995; 2000] |
| A. | 12.5% |
| B. | 87.5% |
| C. | 8.5% |
| D. | 25.1% |
| Answer» C. 8.5% | |
| 3561. |
The count rate of a Geiger- Muller counter for the radiation of a radioactive material of half life of 30 minutes decreases to 5\[{{s}^{-1}}\]after 2 hours. The initial count rate was [CBSE PMT 1995] |
| A. | 25\[{{s}^{-1}}\] |
| B. | 80\[{{s}^{-1}}\] |
| C. | 625\[{{s}^{-1}}\] |
| D. | 20\[{{s}^{-1}}\] |
| Answer» C. 625\[{{s}^{-1}}\] | |
| 3562. |
Unit of radioactivity is Rutherford. Its value is [MP PMT 1994] |
| A. | \[3.7\times {{10}^{10}}\]disi tegrations/sec |
| B. | \[3.7\times {{10}^{6}}\]disintegrations/sec |
| C. | \[1.0\times {{10}^{10}}\] disintegrations/sec |
| D. | \[1.0\times {{10}^{6}}\] disintegrations/sec |
| Answer» E. | |
| 3563. |
In which radioactive disintegration, neutron dissociates into proton and electron [AFMC 1995] |
| A. | \[H{{e}^{++}}\] emission |
| B. | \[\beta -\]emission |
| C. | \[\gamma -\]emission |
| D. | Positron emission |
| Answer» C. \[\gamma -\]emission | |
| 3564. |
16 gm sample of a radioactive element is taken from Bombay to Delhi in 2 hour and it was found that 1 gm of the element remained (undisintegrated). Half life of the element is [MP PMT 1994] |
| A. | 2 hour |
| B. | 1 hour |
| C. | \[\frac{1}{2}hour\] |
| D. | \[\frac{1}{4}hour\] |
| Answer» D. \[\frac{1}{4}hour\] | |
| 3565. |
If 20 gm of a radioactive substance due to radioactive decay reduces to 10 gm in 4 minutes, then in what time 80 gm of the same substance will reduce to 10 gm [MP PMT 1994] |
| A. | In 8 minutes |
| B. | In 12 minutes |
| C. | In 16 minutes |
| D. | In 20 minutes |
| Answer» C. In 16 minutes | |
| 3566. |
If the half-life of a radioactive sample is 10 hours, its mean life is [MP PET 1994] |
| A. | 14.4 hours |
| B. | 7.2 hours |
| C. | 20 hours |
| D. | 6.93 hours |
| Answer» B. 7.2 hours | |
| 3567. |
The half-life of the isotope \[_{11}N{{a}^{24}}\]is 15 hrs. How much time does it take for \[\frac{7}{8}th\] of a sample of this isotope to decay [MP PET 1994] |
| A. | 75 hrs |
| B. | 65 hrs |
| C. | 55 hrs |
| D. | 45 hrs |
| Answer» E. | |
| 3568. |
During a negative beta decay [IIT 1987; MNR 1990] |
| A. | An atomic electron is ejected |
| B. | An electron which is already present within the nucleus is ejected |
| C. | A neutron in the nucleus decays emitting an electron |
| D. | A part of the binding energy is converted into electron |
| Answer» D. A part of the binding energy is converted into electron | |
| 3569. |
The decay constant of a radioactive element is 0.01 per second. Its half-life period is [DPMT 2001] |
| A. | 693 sec |
| B. | 6.93 sec |
| C. | 0.693 sec |
| D. | 69.3 sec |
| Answer» E. | |
| 3570. |
A radioactive element emits 200 particles per second. After three hours 25 particles per second are emitted. The half-life period of element will be |
| A. | 50 minutes |
| B. | 60 minutes |
| C. | 70 minutes |
| D. | 80 minutes |
| Answer» C. 70 minutes | |
| 3571. |
The correct order of ionizing capacity of \[a,\ \beta \]and \[\gamma -\]rays is [CBSE PMT 2000] |
| A. | \[\alpha >\gamma >\beta \] |
| B. | \[\alpha >\beta >\gamma \] |
| C. | \[\alpha <\beta <\gamma \] |
| D. | \[\alpha >\beta >\gamma \] |
| Answer» C. \[\alpha <\beta <\gamma \] | |
| 3572. |
An archaeologist analyses the wood in a prehistoric structure and finds that \[{{C}^{14}}\](Half-life = 5700 years) to \[{{C}^{12}}\]is only one- fourth of that found in the cells buried plants. The age of the wood is about [NCERT 1982] |
| A. | 5700 years |
| B. | 2850 years |
| C. | 11,400 years |
| D. | 22,800 years |
| Answer» D. 22,800 years | |
| 3573. |
Half-life of a radioactive substance is T. The time taken for all the nuclei to disintegrate will be |
| A. | 2T |
| B. | T2 |
| C. | 4T |
| D. | Uncertain |
| Answer» E. | |
| 3574. |
Three \[\alpha -\]particles and one \[\beta -\]particle decaying takes place in series from an isotope \[_{88}R{{a}^{238}}\]. Finally the isotope obtained will be [CPMT 1989; DCE 2000] |
| A. | \[_{84}{{X}^{220}}\] |
| B. | \[_{86}{{X}^{222}}\] |
| C. | \[_{83}{{X}^{224}}\] |
| D. | \[_{83}{{X}^{215}}\] |
| Answer» D. \[_{83}{{X}^{215}}\] | |
| 3575. |
Curie is a unit of |
| A. | Length |
| B. | It is not any unit |
| C. | Activity |
| D. | Atomic number |
| Answer» D. Atomic number | |
| 3576. |
The half-life period of radium is 1600 years. The fraction of a sample of radium that would remain after 6400 years is [NCERT 1980; SCRA 1994; JIPMER 1997 CBSE PMT 1994; MNR 1998; MP PMT 2004; DPMT 2004] |
| A. | \[\frac{1}{4}\] |
| B. | \[\frac{1}{2}\] |
| C. | \[\frac{1}{8}\] |
| D. | \[\frac{1}{16}\] |
| Answer» E. | |
| 3577. |
A sample contains 16 gm of a radioactive material, the half life of which is two days. After 32 days, the amount of radioactive material left in the sample is [NCERT 1984; MNR 1995; MP PMT 1995] |
| A. | Less than 1 mg |
| B. | \[\frac{1}{4}gm\] |
| C. | \[\frac{1}{2}gm\] |
| D. | 1 gm |
| Answer» B. \[\frac{1}{4}gm\] | |
| 3578. |
Atomic mass number of an element thorium is 232 and its atomic number is 90. The end product of this radioactive element is an isotope of lead (atomic mass 208 and atomic number 82). The number of alpha and beta particles emitted is [CPMT 1985; Pb. PET 2003] |
| A. | \[\alpha =3,\ \beta =3\] |
| B. | \[\alpha =6,\ \beta =4\] |
| C. | \[\alpha =6,\ \beta =0\] |
| D. | \[\alpha =4,\ \beta =6\] |
| Answer» C. \[\alpha =6,\ \beta =0\] | |
| 3579. |
Which of the following is not a mode of radioactive decay [NCERT 1978] |
| A. | Positron emission |
| B. | Electron capture |
| C. | Fusion |
| D. | Alpha decay |
| Answer» D. Alpha decay | |
| 3580. |
Half-life of radioactive element depends upon [NCERT 1978; AFMC 1996] |
| A. | Amount of element present |
| B. | Temperature |
| C. | Pressure |
| D. | Nature of element |
| Answer» E. | |
| 3581. |
Radioactivity is |
| A. | Irreversible process |
| B. | Self disintegration process |
| C. | Spontaneous process |
| D. | All of the above |
| Answer» E. | |
| 3582. |
A radioactive nucleus undergoes a series of decay according to the scheme \[A\xrightarrow{\alpha }{{A}_{1}}\xrightarrow{\beta }{{A}_{2}}\xrightarrow{\alpha }{{A}_{3}}\xrightarrow{\gamma }{{A}_{4}}\] If the mass number and atomic number of A are 180 and 72 respectively, then what are these number for A4 [Roorkee 1986; MP PET 2002; KCET 2003; DPMT 2005] |
| A. | 172 and 69 |
| B. | 174 and 70 |
| C. | 176 and 69 |
| D. | 176 and 70 |
| Answer» B. 174 and 70 | |
| 3583. |
The half-life of \[B{{i}^{210}}\]is 5 days. What time is taken by (7/8)th part of the sample to decay [MNR 1986; Pb. PMT 2001] |
| A. | 3.4 days |
| B. | 10 days |
| C. | 15 days |
| D. | 20 days |
| Answer» D. 20 days | |
| 3584. |
In a radioactive substance at \[t=0\], the number of atoms is \[8\times {{10}^{4}}\]. Its half life period is 3 years. The number of atoms \[1\times {{10}^{4}}\] will remain after interval [MP PMT/PET 1988] |
| A. | 9 years |
| B. | 8 years |
| C. | 6 years |
| D. | 24 years |
| Answer» B. 8 years | |
| 3585. |
Which of the following is in the increasing order for penetrating power [IIT 1994; RPET 2003] |
| A. | \[\alpha ,\ \beta ,\ \gamma \] |
| B. | \[\beta ,\ \alpha ,\ \gamma \] |
| C. | \[\gamma ,\ \alpha ,\ \beta \] |
| D. | \[\gamma ,\ \beta ,\ \alpha \] |
| Answer» B. \[\beta ,\ \alpha ,\ \gamma \] | |
| 3586. |
If the decay or disintegration constant of a radioactive substance is\[\beta \], then its half life and mean life are respectively [IIT 1989; MNR 1990; MP PET 1995, 97, 99, 2002; MP PMT 1999, 2002; UPSEAT 2002] |
| A. | \[\begin{matrix} 1 \\ \lambda \\ \end{matrix}\] and \[\frac{{{\log }_{e}}2}{\lambda }\] |
| B. | \[\frac{{{\log }_{e}}2}{\lambda }\]and \[\begin{matrix} 1 \\ \lambda \\ \end{matrix}\] |
| C. | \[\lambda \ {{\log }_{e}}2\]and\[\begin{matrix} 1 \\ \lambda \\ \end{matrix}\] |
| D. | \[\begin{matrix} \lambda \\ {{\log }_{e}}2 \\ \end{matrix}\] and \[\begin{matrix} 1 \\ \lambda \\ \end{matrix}\] (loge 2 can be written as ln 2) |
| Answer» C. \[\lambda \ {{\log }_{e}}2\]and\[\begin{matrix} 1 \\ \lambda \\ \end{matrix}\] | |
| 3587. |
If T is the half-life of a radioactive material, then the fraction that would remain after a time \[\frac{T}{2}\] is [MP PMT 1992] |
| A. | \[\frac{1}{2}\] |
| B. | \[\frac{3}{4}\] |
| C. | \[\frac{1}{\sqrt{2}}\] |
| D. | \[\frac{\sqrt{2}-1}{\sqrt{2}}\] |
| Answer» D. \[\frac{\sqrt{2}-1}{\sqrt{2}}\] | |
| 3588. |
Consider two nuclei of the same radioactive nuclide. One of the nuclei was created in a supernova explosion 5 billion years ago. The other was created in a nuclear reactor 5 minutes ago. The probability of decay during the next time is [KCET 2005] |
| A. | Different for each nuclei |
| B. | Nuclei created in explosion decays first |
| C. | Nuclei created in the reactor decays first |
| D. | Independent of the time of creation |
| Answer» E. | |
| 3589. |
In a sample of radioactive material, what fraction of the initial number of active nuclei will remain undisintegrated after half of a half-life of the sample [Kerala PMT 2005] |
| A. | \[\frac{1}{4}\] |
| B. | \[\frac{1}{2\sqrt{2}}\] |
| C. | \[\frac{1}{\sqrt{2}}\] |
| D. | \[2\sqrt{2}\] |
| Answer» D. \[2\sqrt{2}\] | |
| 3590. |
In a radioactive reaction \[_{92}{{X}^{232}}{{\to }_{82}}{{Y}^{204}}\], the number of \[\alpha -\]particles emitted is [BCECE 2005] |
| A. | 7 |
| B. | 6 |
| C. | 5 |
| D. | 4 |
| Answer» B. 6 | |
| 3591. |
If half-life of radium is 77 days. Its decay constant in day will be [BCECE 2005] |
| A. | \[3\times {{10}^{-13}}\]/day |
| B. | \[9\times {{10}^{-3}}\]/day |
| C. | \[1\times {{10}^{-3}}\]/day |
| D. | \[6\times {{10}^{-3}}\]/day |
| Answer» C. \[1\times {{10}^{-3}}\]/day | |
| 3592. |
The phenomenon of radioactivity is [BHU 2005] |
| A. | Exothermic change which increases or decreases with temperature |
| B. | Increases on applied pressure |
| C. | Nuclear process does not depend on external factors |
| D. | None of the above |
| Answer» D. None of the above | |
| 3593. |
\[_{86}{{A}^{222}}{{\to }_{84}}{{B}^{210}}\]. In this reaction how many \[\alpha \] and \[\beta \] particles are emitted [BHU 2005] |
| A. | \[6\alpha ,\,3\beta \] |
| B. | \[3\alpha ,\,4\beta \] |
| C. | \[4\alpha ,\,3\beta \] |
| D. | \[3\alpha ,\,6\beta \] |
| Answer» C. \[4\alpha ,\,3\beta \] | |
| 3594. |
Mean life of a radioactive sample is 100 seconds. Then its half-life (in minutes) is [KCET 2005] |
| A. | 0.693 |
| B. | 1 |
| C. | 10-4 |
| D. | 1.155 |
| Answer» E. | |
| 3595. |
The average life T and the decay constant \[\lambda \] of a radioactive nucleus are related as [CPMT 1983] |
| A. | \[T\lambda =1\] |
| B. | \[T=\frac{0.693}{\lambda }\] |
| C. | \[\frac{T}{\lambda }=1\] |
| D. | \[{{\lambda }_{1}},\ {{\lambda }_{2}},\ {{\lambda }_{3}}\] |
| Answer» B. \[T=\frac{0.693}{\lambda }\] | |
| 3596. |
Nuclear fusion is common to the pair [MP PMT 2005] |
| A. | Thermonuclear reactor, uranium based nuclear reactor |
| B. | Energy production in sun, uranium based nuclear reactor |
| C. | Energy production in sun, hydrogen bomb |
| D. | Disintegration of heavy nuclei, hydrogen bomb |
| Answer» D. Disintegration of heavy nuclei, hydrogen bomb | |
| 3597. |
\[{{C}^{14}}\] has half-life 5700 years. At the end of 11400 years, the actual amount left is [MP PET 2005] |
| A. | 0.5 of original amount |
| B. | 0.25 of original amount |
| C. | 0.125 of original amount |
| D. | 0.0625 of original amount |
| Answer» C. 0.125 of original amount | |
| 3598. |
A nucleus of mass 218 amu in free state decays to emit an a-particle. Kinetic energy of the a-particle emitted is 6.7 MeV. The recoil energy (in MeV) of the daughter nucleus is [EAMCET 2005] |
| A. | 1.0 |
| B. | 0.5 |
| C. | 0.25 |
| D. | 0.125 |
| Answer» E. | |
| 3599. |
The composition of an a-particle can be expressed as [CPMT 2005] |
| A. | \[1P+1N\] |
| B. | \[1P+2N\] |
| C. | \[2P+1N\] |
| D. | \[2P+2N\] |
| Answer» E. | |
| 3600. |
\[_{90}^{232}Th\] an isotope of thorium decays in ten stages emitting six a-particles and four b-particles in all. The end product of the decay is [CPMT 2005] |
| A. | \[_{82}^{206}Pb\] |
| B. | \[_{82}^{209}Pb\] |
| C. | \[_{82}^{208}Pb\] |
| D. | \[_{83}^{209}Br\] |
| Answer» D. \[_{83}^{209}Br\] | |