320 + Interview Questions in NUCLEI IN GENERAL AWARENESS Page 7 InterviewSolution

301.	How long can an electric lamp of 100W be kept glowing by fusion of 2.0 kg of deuterium? The fusion reaction can be taken as `._1H^2+._1H^2to ._1H^3+n+3.17MeV`A. `2.4xx10^6` yearsB. `7.4xx10^4` yearsC. `1.6xx10^6` yearsD. `4.9xx10^4` years
Answer» Correct Answer - d Number of atoms present in 2 g of deuterium `=(6.023xx10^23xx2000)/2=6.023xx10^26` Energy released in the fusion of 2 deuterium atoms =3.27 MeV Total energy released in the fusion of 2.0 kg of deuterium atoms `E=3.27/2xx6.023xx10^26=9.81xx10^26` MeV `=15.696xx10^13` J Energy consumed by the bulb per second = 100 J Time for which the bulb will glow `t=(15.69xx10^13)/100 s` or `t=(15.69xx10^11)/(3.15xx10^7)` years `=4.9xx10^4` years .

Discussion

302.	How long can an electric lamp of 100W be kwpt glowing by fusion of 2.0 kg of deuterium ? Take fusion reaction as `._(1)^(2)H+._(1)^(2)Hto ._(2)^(3)He+n+3.27 MeV`
Answer» Number of deuterium atoms in 2.0 kg `= (6.023xx10^(23)xx2000)/(2)=6.023xx10^(26)` Energy released when 2 atoms fuse = 3.27 MeV `therefore` Total energy released `=(3.27)/(2)xx6.023xx10^(26)MeV` `= 1.635xx6.023xx10^(26)xx1.6xx10^(-13)J` `= 15.75xx10^(3)J` Energy consumed by the bulb/sec = 100 J `therefore` Time for which bulb will glow `= (15.75xx10^(13))/(100)S` `= (15.75xx10^(11))/(60xx60xx24xx365)=4.99xx10^(7)` years

Discussion

303.	How long an electric lamp of 100 W can be kept glowing by fusion of 2.0 kg of deuterium? The fusion reaction as.21H + 21H → 32He + n + 3.27 MeV
Answer» Number of deuterium atoms is 2 kg = \(\frac{6.023\times10^{23}}{2}\times2000\) = 6.023 × 10²⁶ Energy released when 6.023 × 10²³ nuclei of deuterium fuse together = \(\frac{3.2}{2}\times6.023\times10^{26}MeV\) = \(\frac{3.2\times6.023\times10^{26}}{2}\times1.6\times10^{-13}J\) = 15.42 × 10¹³ J = 15.42 Ws Power of lamp = 100 W If the lamp glows for time t, then electric energy consumed = 100 t ∴ 100 t = 15.42 × 10³³ ∴ t = 0.1542 × 10¹³ s = \(\frac{0.1542\times10^{13}}{365\times86400}y\) or t = 4.0 × 10⁴ y

303.

How long an electric lamp of 100 W can be kept glowing by fusion of 2.0 kg of deuterium? The fusion reaction as.21H + 21H → 32He + n + 3.27 MeV

Answer»

Number of deuterium atoms is 2 kg

= \(\frac{6.023\times10^{23}}{2}\times2000\) = 6.023 × 10²⁶

Energy released when 6.023 × 10²³ nuclei of deuterium fuse together

= \(\frac{3.2}{2}\times6.023\times10^{26}MeV\)

= \(\frac{3.2\times6.023\times10^{26}}{2}\times1.6\times10^{-13}J\)

= 15.42 × 10¹³ J = 15.42 Ws

Power of lamp = 100 W

If the lamp glows for time t, then electric energy consumed = 100 t

∴ 100 t = 15.42 × 10³³

∴ t = 0.1542 × 10¹³ s

= \(\frac{0.1542\times10^{13}}{365\times86400}y\)

or t = 4.0 × 10⁴ y

Discussion

304.	Fusion reaction takes place at high temperature becauseA. At high temperature atoms are ionisedB. Al high temperature molecules break-upC. At high temperature nuclei break-upD. To overcome repulsion between nuclei kinetic energy should be high enough
Answer» Correct Answer - D

Discussion

305.	Fusion reaction takes place at high temperature because(a) nuclei break up at high temperature(b) atoms get ionized at high temperature(c) kinetic energy is high enough to overcome the coulomb repulsion between nuclei (d) molecules break up at high temperature
Answer» (c) kinetic energy is high enough to overcome the coulomb repulsion between nuclei.

Discussion

306.	Explain `beta` - decay ?
Answer» 1. It is the phenomenon of emission of an electron from a radioactive nucleus. 2. When a parent nucleus emits a `beta` - particle (i.e., an electron), mass number remains same because mass of electron is negligibly low. However, the loss of unit negative charge is equivalent to a gain of unit positive charge. Therefore, atomic number is increased by one. 3. In general, we can write `._(Z)X^(A) rarr ._(Z+1)Y^(A)+ . _(-1)e^(0)+Q` where Q is the energy released in `beta` - decay. 4. The basic nuclear process underlying `beta` - decay is the conversion of neutron to proton. `n rarr P + bar(e)+bar(v)` While for `beta+` decay, it is the conversion of proton ino neutron. `P rarr n+ e^(+)+v` 5. The emiision of electron in `beta`- decay is accompained by the emission of an anti neutrino `bar(v))` In `beta`, decay insted, a neutrino (v) is generated. Neutrons are neutral particles with very small mass compared to electrons. They have only weak interactions with other particles.

Discussion

307.	Fusion raction takes place at high temperature becauseA. molecules break up at high termperatureB. nuclei break up at high temperatureC. atoms get ionsed at high temperatureD. kintic energy is high enough to over come the coulomb repulsion between nuclei
Answer» Correct Answer - d Fusion feaction takes place at high temperature because kinetic energy is high enough to covercome the Coulomb repulsion between nuclei.

Discussion

308.	For greater stability a nucleus should have greater value of binding energy per nucleon. Why ?
Answer» 1. Uranium has a relatively low binding energy per nucleon as 7.6 MeV. Hence to attain greater stability Uranium breaks up into intermediate mass nuclei resulting in a phenomenon called nuclear nuclear fission. 2. Lighter nuclei such as hydrogen combine to form heavy nucleus to form helium for greater stability, resulting in a phenomenon called nuclear fusion. 3. Iron whose binding energy per nucleon stands maximum at 8.7 MeV is the most stable and will undergo neither fission nor fusion.

Discussion

309.	Nuclear fusion is common to the pairA. thermonuclear reactor , uranium based nuclear rectorB. energy producation in sun , uranium based nucleat reactorC. energy producation insun ,hyducation in sun , hydrogen bombD. disntegration of heavy nuclei , hydrogen bomb
Answer» Correct Answer - c The energy released in sun and hydrogen bomb are due t nuclear fusion.

Discussion

310.	Statement-1:In a nuclear reaction energy is released , if total binding energy is increasing. Statement-2:For a stability of a nucleus, total binding energy is more important than binding energy per nucleon. Statement-3:Nuclear force is different for different nucleons and it dependent on charge .A. TFTB. FFFC. TTFD. TFF
Answer» Correct Answer - D

Discussion

311.	In Column-I , name of radiation is given and in column-II, reaction for radiation and nucleus phenomena .
Answer» Correct Answer - A::B::C::D

Discussion

312.	Which pair is isotonic?A. `""_(7)N^(13),""_(7)N^(14)`B. `""_(6)C^(14),""_(6)C^(12)`C. `""_(6)C^(14),""_(7)C^(14)`D. `""_(7)N^(13),""_(6)C^(12)`
Answer» Correct Answer - D Since, `N=13-7=6,C=12-6=6`

Discussion

313.	Pick out the correct statement from the followingA. Energy released per unit mass of the reactant is less in case of fusion reactionB. parcking fraction may be postitive or may be negativeC. `Pu^(239)` is not suitable for a fission reactionD. for stable nucleus , the specific bonding energy is low
Answer» Correct Answer - b Heavy water is uses as moderator in a nuclear reacor. The function of the moderator is to show down the netrons of thermal energies.

Discussion

314.	Pick out the correct statement from the following.A. `alpha`-particles are not deflected by electric and magnetic field.B. `beta`-particle has less penetrating power than `alpha`-particles.C. `gamma`-rays has the least ionising power than `alpha and beta` particlesD. `gamma`-rays has the least penetrating power than `alpha and beta` rays
Answer» Correct Answer - C `gamma`-rays, ionis gases but their ionisation power is very small compared to that of `alpha and beta`-particles.

Discussion

315.	Radioactivity of a sample at `T_(1)` time is `R_(1)` and at time `T_(2)` is `R_(2).` If half-life of sample is T, then in time `(T_(2)-T_(1)),` the number of decayed atoms is proportional toA. `R_(1)T_(2)-R_(2)T_(2)`B. `(R_(1)-R_(2))T`C. `((R_(1)-R_(2)))/(T)`D. `R_(1)-R_(2)`
Answer» Correct Answer - B Let `R_(1)=N_(1)lamdaandR_(2)=N_(2)lamda` Mean life, `T=(1)/(lamda)` `R_(1)-R_(2)=(N_(1)-N_(2))lamda=(N_(1)-N_(2))(1)/(T)` So, number of atoms disintegrated in `(T_(2)-T_(1))` is `=N_(1)-N_(2)=(R_(1)-R_(2))T`

Discussion

316.	Match the statement in Column I to the appropriate statement(s) from Column II.
Answer» Correct Answer - `(Ato r;s Bto q; Cto p; Dto p)` (i) stability of nucleus is decided by neutron-proton ratio , packing grachtion and binding energy per nucleon . (ii) for radioactive substance binding energy per nucleon is minimum . So they are unstable . (iii) for bound orbit , total energy is always nagative . (iv) stopping potential is the particular negative potential when no electron reches the plate .

Discussion

317.	Alpha rays emitted from a radioactive substance areA. negatively charged particlesB. ionised hydrogen nucleiC. doubly ionised helium atomD. uncharged particles having the mass equal to proton
Answer» Correct Answer - C Alpha rays emitted from a radioactive substance are doubly ionised helium atom.

Discussion

318.	The phenomenon of radioactivityA. increases on applied pressureB. is exothermic change which increases or decreases with temperatureC. is nuclear process which does not depend on external forceD. None of the aobve
Answer» Correct Answer - C Phenomenon of radioactivity is a nuclear process which does not depend on external forces.

Discussion

319.	From a radioactive substance x numbers of `alpha`-particles any y numbers of `beta`-particles are emitted. As a result atomic number decreases by n and mass number by m. Then, match the following two columns.
Answer» Correct Answer - `(Atoq; Btos; Cto p; Dtor)` By the emission of an `alpha`-particle , atomic number decreases by 2nd mass number by 4. but by the emission of a `beta `-particle atomic number increase increase by 1 while mass number remains unchanged .

Discussion

320.	Assertion If high pressur is applied on a radioactive substance rate of radioactivity is a nuclear process.A. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.B. If both Assertion and Reason are true but Reason are true but Reason is not correct explanation of Assertion.C. If Assertion is true but Reason is false.D. If Assertion is false but Reason is true.
Answer» Correct Answer - D (d) Rate of a nuclear process cannot be altered by altering pressure or temperature .

Discussion

Explore topic-wise InterviewSolutions in .

How long can an electric lamp of 100W be kept glowing by fusion of 2.0 kg of deuterium? The fusion reaction can be taken as `._1H^2+._1H^2to ._1H^3+n+3.17MeV`A. `2.4xx10^6` yearsB. `7.4xx10^4` yearsC. `1.6xx10^6` yearsD. `4.9xx10^4` years

How long can an electric lamp of 100W be kwpt glowing by fusion of 2.0 kg of deuterium ? Take fusion reaction as `._(1)^(2)H+._(1)^(2)Hto ._(2)^(3)He+n+3.27 MeV`

How long an electric lamp of 100 W can be kept glowing by fusion of 2.0 kg of deuterium? The fusion reaction as.21H + 21H → 32He + n + 3.27 MeV

Fusion reaction takes place at high temperature becauseA. At high temperature atoms are ionisedB. Al high temperature molecules break-upC. At high temperature nuclei break-upD. To overcome repulsion between nuclei kinetic energy should be high enough

Fusion reaction takes place at high temperature because(a) nuclei break up at high temperature(b) atoms get ionized at high temperature(c) kinetic energy is high enough to overcome the coulomb repulsion between nuclei (d) molecules break up at high temperature

Explain `beta` - decay ?

Fusion raction takes place at high temperature becauseA. molecules break up at high termperatureB. nuclei break up at high temperatureC. atoms get ionsed at high temperatureD. kintic energy is high enough to over come the coulomb repulsion between nuclei

For greater stability a nucleus should have greater value of binding energy per nucleon. Why ?

Nuclear fusion is common to the pairA. thermonuclear reactor , uranium based nuclear rectorB. energy producation in sun , uranium based nucleat reactorC. energy producation insun ,hyducation in sun , hydrogen bombD. disntegration of heavy nuclei , hydrogen bomb

In Column-I , name of radiation is given and in column-II, reaction for radiation and nucleus phenomena .

Which pair is isotonic?A. `""_(7)N^(13),""_(7)N^(14)`B. `""_(6)C^(14),""_(6)C^(12)`C. `""_(6)C^(14),""_(7)C^(14)`D. `""_(7)N^(13),""_(6)C^(12)`

Pick out the correct statement from the followingA. Energy released per unit mass of the reactant is less in case of fusion reactionB. parcking fraction may be postitive or may be negativeC. `Pu^(239)` is not suitable for a fission reactionD. for stable nucleus , the specific bonding energy is low

Radioactivity of a sample at `T_(1)` time is `R_(1)` and at time `T_(2)` is `R_(2).` If half-life of sample is T, then in time `(T_(2)-T_(1)),` the number of decayed atoms is proportional toA. `R_(1)T_(2)-R_(2)T_(2)`B. `(R_(1)-R_(2))T`C. `((R_(1)-R_(2)))/(T)`D. `R_(1)-R_(2)`

Match the statement in Column I to the appropriate statement(s) from Column II.

Alpha rays emitted from a radioactive substance areA. negatively charged particlesB. ionised hydrogen nucleiC. doubly ionised helium atomD. uncharged particles having the mass equal to proton

The phenomenon of radioactivityA. increases on applied pressureB. is exothermic change which increases or decreases with temperatureC. is nuclear process which does not depend on external forceD. None of the aobve

From a radioactive substance x numbers of `alpha`-particles any y numbers of `beta`-particles are emitted. As a result atomic number decreases by n and mass number by m. Then, match the following two columns.