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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.
| 201. |
A radioactive isotope`A` undergoes simultaneous decay to two different nuclei as Assuming that initially neither `P` nor`Q` was present, after how many hours, amount of `Q` will be just double to the amount of `A` remaining?A. Both Assertion and Reason are correct and Reason is the correct explanation of the AssertionB. Both Assertion and Reason are correct but Reason is not the correct explanation of AssertionC. Assertion is correct but Reason is incorrectD. Assertion is incorrect but Reason is correct |
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Answer» Correct Answer - 6 |
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| 202. |
`T_(1//2) " of "C^(14)` isotope is 5770 years. Time after which 72% of isotope left isA. 2740 yearsB. 274 yearsC. 2780 yearsD. 278 years |
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Answer» Correct Answer - A `K = (0.693)/(T_(1//2)) = (0.693)/(5770)` `:. t = (2.303)/(K)"log"(100)/(72) = (2.303 xx 5770)/(0.693) "log" (100)/(72)` `= 19175.05 xx (log 100 - log 72)` `19175.05 xx 0.143 = 2742.03` years |
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| 203. |
A wood piece is 11460 years old. What is the fraction of `.^(14)C` activity left in the piece (Half-life period of `.^(14)C` is 5730 years)A. 0.12B. 0.25C. 0.5D. 0.75 |
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Answer» Correct Answer - B 11460 years = 2 half lives Activity left = 25%= 0.25 |
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| 204. |
Assertion : Radioactive heavy nuclei decay by a series of `alpha- and //or beta-`emission, to form a stable isotope of lead Reaosn : Radioactivity is a physical phenomenonA. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanantion of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false |
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Answer» Correct Answer - D At onetime, it was believed that actinium series starts with `Ac -227` but now it is well known that it starts with `U - 235 and Ac -227` is one of the main products |
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| 205. |
The half-life for decay of `.^(14)C " by " beta-`emission is 5730 years. The fraction of `.^(14)C` decays, in a sample that is 22,920 years old, would beA. `1//8`B. `1//16`C. `7//8`D. `15//16` |
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Answer» Correct Answer - D `N = N_(0) ((1)/(2))^(t//t_((1)/(2))) = N_(0) ((1)/(2))^((22920)/(5730)) = N_(0) ((1)/(2))^(4) = (N_(0))/(16)` where `N_(0)`= initial amount, N =amount left so fraction reacted `N_(0) - (N_(0))/(16) = (15)/(16) N_(0)` |
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| 206. |
In the radioacitve decay `._(Z)X^(A) rarr ._(z + 1)Y^(A) rarr ._(z - 1)^(A - 4) rarr ._(z - 1)Z^(*A - 4)` The sequence of emission is a. `alpha, beta, gamma` b. `gamma, alpha, beta` c. `beta, alpha, gamma` c. `beta, gamma, alpha` |
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Answer» `._(z)X^(A) - ._(-1)e^(0) rarr ._(z + 1)Y^(A)` `._(z + 1)Y^(A) - ._(2)He^(4) rarr ._(z - 1)Z^(A - 4)` `._(z - 1)Z^(A - 4) - gamma rarr ._(z - 1)Z^(*A - 4)` |
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| 207. |
`Na""^(22)` has half life of 2.68 years. It decays both by positron emission and electron capture with a ratio of 86% of the former to 14% of the later. The half life for positron emission in years (nearly) is |
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Answer» Correct Answer - 3 `lamda""_(1)/lamda""_(2)=14/86,(lamda=2.303/tlog"N""_(0)/N),` `lamda=lamda""_(1)+lamda""_(2)` `0.693/2.68=(lamda""_(2)xx14)/86+lamda""_(2)02` `0.258=lamda""_(2)(14/86+1)` `0.258=lamda""_(2)(100/86)` lamda""_(2)=(86xx0.258)/(100),t""_(1//2)=0.693/lamda""_(2)` |
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| 208. |
An element X decays first by positron emission and then two `alpha`-particles are emitted in succesive radioactive decay. If the product nucleus has a mass number 229 andd atomic number 89, the mass number and atomic number of element X areA. 273,93B. 237,94C. 238,93D. 237,92 |
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Answer» Correct Answer - b Protons are never given out during radioactive change. |
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| 209. |
The radioactive nuclide `""_(90)""^(234)Th` shows two succesive `beta`-decay followed by one `alpha`-decay. The atomic nuimber and mass number respectively of the resulting atom isA. 90 and 230B. 92 and 230C. 92 and 234D. 94 and 230 |
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Answer» Correct Answer - a During the emmision of `alpha` particle `Zdarr` by 2 units and `Adarr` by 4 units . During the emmision of `beta` particle `Zuarr` by 1 unit and A doesn t change `2""^(n)=N""_(0)/N=(15.5-1.5)/3.5=4,n=2` |
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| 210. |
Assertion : An example of K-capture is `._(56)^(133)Ba + e^(-) rarr ._(55)^(133)Cs + X`-ray. Reason : The atomic number decreases by one unit as result of K-captureA. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanantion of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false |
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Answer» Correct Answer - B In some nuclides, the nucleus may capture an electron from the K--shell and the vacancy created is filled by electrons from higher levels giving rise to characteristic X-rays. This process is known as K-electron capture or simply K-capture. |
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| 211. |
`""_(88)""^(224)Ra` decays by a series emmision of three `beta-` particles and two `alpha-`particles. The end product of X isA. `""_(88)""^(220)X`B. `""_(87)""^(216)X`C. `""_(90)""^(234)X`D. `""_(88)""^(216)X` |
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Answer» Correct Answer - b During the emission of `alpha` particle `Zdarr` by 2 units and `Adarr` by 4 units During the emmision of `beta` particle `Zuarr` by 1 unit and A doesn t change |
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| 212. |
Assertion `(A): gamma-` rays have very high penetrating power. Reason `(R) : gamma-` rays are high `-` energy electromagnetic radiations.A. If both `(A)` and `(R)` are correct , and `(R)` is the correct explanation of `(A)`B. If both `(A)` and `(R)` are correct, but (R) is not the correct explanation of `(A)`C. If `(A)` is correct, but `(R)` is incorrect.D. If `(A)` is incorrect, but `(R)` is correct. |
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Answer» Correct Answer - A `gamma-` rays are high`-`energy radiations and have high penetrating power. |
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| 213. |
The radiations having high penetrating power and not affected by electrical and magnetic field areA. `gamma`-raysB. neutronsC. `beta`-raysD. `alpha`-particles |
| Answer» Correct Answer - a | |
| 214. |
The radiations have high penetrating power and not affected by electrical and magnetic field areA. Alpha raysB. Beta raysC. Gamma raysD. Neutrons |
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Answer» Correct Answer - C `gamma`-rays have maximum penetrating power |
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| 215. |
Two isotopes `P` and `Q` atomic weight `10` and `20`, respectively are mixed in equal amount by weight. After `20` days their weight ratio is found to be `1:4`. Isotope `P` has a half-life of `10` days. The half-life of isotope `Q` isA. ZeroB. 5 dayC. 20 dayD. Infinite |
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Answer» Correct Answer - c p=w q=w No. of `p=w/4` `q=4xxw/4`,`2""^(n)=w/w=2` `n=1,t=t""_(1//2)=20` |
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| 216. |
The half-life of radium is 16000 yr, after how much time will 1 g radium be reduced to 125 mg?A. 800 yrB. 1600 yrC. 3200 yrD. 4800 yr |
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Answer» Correct Answer - d Given, `t_(1//2) = 1600 yr, N_(0) = 1 g, N = 125 mg = (125)/(1000)g` We know that, `N = N_(0)((1)/(2))^((t)/(t_(1//2)))` `(125)/(1000) = ((1)/(2))^(t//1600), (1)/(8) or ((1)/(2))^(3) = ((1)/(2))^(t//1600)` Hence, `(t)/(1600) = 3 or t = 3xx1600 = 4800 yr` |
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| 217. |
The time in which activity of an element is reduced to 90% of its original value is (given `t""_(1//2)=1.4xx10""^(10)yr`)A. `1.128xx10""^(9)year`B. `2.128xx10""^(9)year`C. `3.128xx10""^(9)year`D. None of these |
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Answer» Correct Answer - b `lamda=2.303/tlog.N""_(0)/N(lamda=0.693//t""_(1//2))` |
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| 218. |
Isosters are compounds having similar geometry and isoelectronic species are species having the same number of electrons. The pair of species `CO_(2)` and `NO_(2)` isA. isosteric and isoelectronicB. isosteric, but not isoelectronicC. isoelectronic, but not isostericD. neither isosteric nor isoelectronic |
| Answer» Correct Answer - A | |
| 219. |
The phenomenon which suggested that light emitted in packets (quanta) isA. electron diffractionB. photoelectric effectC. diffraction of lightD. black body radiation. |
| Answer» Correct Answer - B | |
| 220. |
If by mistake some radioactive substance gets inside the human body, then form the point of view of radiation damage, the most harmful will be one which emitsA. `gamma`-raysB. NeutronsC. `beta-`particlesD. `alpha-`particle |
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Answer» Correct Answer - A `gamma-`rays have maximum penetrating power |
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| 221. |
The mean lives of a radioactive substance are 1620 years and 405 years of `alpha`-emission and `beta`-emission respectively. Find out the time during which three-fourth of a sample will decay if it is decaying both by `alpha`-emission and `beta`-emission simultaneously. |
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Answer» For succiessive `alpha, beta`-emission `K_("avg") = K_(alpha) + K_(beta) = (1)/(1620) + (1)/(405) = (5)/(1620) "years"^(-1)` Given at `t = t`, `N = 1//4 N_(0)` (since `3//4` part decays) `t = (2.303)/(K_("avg")) "log" (N_(0))/(N)` `= (2.303 xx 1620)/(5) "log" 4 = 449.24` years |
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| 222. |
A `0.20 mL` sample of a solution containing `1.0 xx 10^(-7) Ci` of `._(1)H^(3)` is injected into the blood stream of a laboratory animal. After sufficient time of of a circulatory equilibrium to be established, `0.10 mL` of blood is found to have an activity of 20 dpm. Calculate the blood volume of the animal. |
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Answer» In the injected sample the activity is `(1.0 xx 10^(7) Ci) ((3.7 xx 10^(10) dps)/(Ci)) = 3.7 xx 10^(3) dps` In the sample withdraw `= (20 dpm)` `(1 "min"//60 s)` `= 0.33 dps` The total activity of the entire blood volume is equal to the activity of the sample injected. The ratio of volumes, where `V` is the original body blood volume: `(3.7 xx 10^(3) dps)/(0.33 dps) = (V + 0.20 mL)/(0.10 mL)` `V = 1.1 xx 10^(3) mL = 1.1 L` |
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| 223. |
What is `X` in the nuclear reaction `._(7)N^(14) + ._(1)H^(1) rarr ._(8)O^(15) + X`A. `._(+1)e^(0)`B. `._(0)n^(1)`C. `gamma`-raysD. `._(-1)e^(0)` |
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Answer» Correct Answer - C `._(7)N^(14) + ._(1)H^(1) rarr ._(8)O^(15)+ gamma`, because X is the `gamma`-rays it has neither mass nor charge |
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| 224. |
Alpha rays consist of a stream ofA. `H^(+)`B. `He^(+2)`C. Only electronsD. Only neutrons |
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Answer» Correct Answer - B `alpha`-rays consist of a stream of `He^(2+)` |
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| 225. |
A deutron containsA. A neutron and a positronB. A neutron and a protonsC. A neutron and two protonsD. A proton and two neutrons |
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Answer» Correct Answer - B A deutron `(._(1)H^(2))` contains a neutron and a proton |
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| 226. |
In a nuclear explosion, the energy is released in the form ofA. Kinetic energyB. Electrical energyC. Potential energyD. None of these |
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Answer» Correct Answer - D Nuclear reactions involve exchange of nuclear energy |
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| 227. |
`._(6)C^(12) and ._(1)T^(3)` are formed in nature due to the nuclear reaction of neutron withA. `._(7)N^(14)`B. `._(6)C^(13)`C. `._(2)He^(4)`D. `._(3)Li^(6)` |
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Answer» Correct Answer - A The balanced equation is `._(7)N^(14) + ._(0)n^(1) rarr ._(6)C^(12) + ._(1)T^(3)` `._(1)T^(3)` (Tritium) is a radioactive isotope of hydrogen |
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| 228. |
Which one of the following nuclear reaction is correctA. `._(6)C^(13) + ._(1)H^(1) rarr ._(7)N^(13) + beta^(-) + v^(-)`B. `._(11)Na^(23) + ._(1)H^(1) rarr ._(10)Ne^(20) + ._(2)He^(4)`C. `._(13)Al^(23) + ._(0)n^(1) rarr ._(11)Na^(23) + e^(0)`D. None of these |
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Answer» Correct Answer - B Equate mass number and atomic number on both sides. |
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| 229. |
`alpha`-particles can be detected usingA. Thin aluminumB. Barium sulphateC. Zinc sulphide screenD. Gold foil |
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Answer» Correct Answer - C Rutherford first of all used zinc sulphate (ZnS) as phosphor in the detection of `alpha`-particles |
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| 230. |
If uranium (mass number 238 and atomic number 92) emits an `alpha-` particle, the product has mass no. and atomic no.A. 236 and 92B. 234 and 90C. 238 and 90D. 236 and 90 |
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Answer» Correct Answer - B `.^(92)U^(238) rarr ._(90)U^(234) + ._(2)^(4)He` |
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| 231. |
Which of the following is the most stable?A. BiB. AlC. UD. Pb |
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Answer» Correct Answer - D Pb is the most stable atom |
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| 232. |
The `._(88)Ra^(226)` isA. n-mesonsB. u-mesonsC. RadioactiveD. Non-radioactive |
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Answer» Correct Answer - C `._(88)Ra^(226)` is radioactive because `(n)/(p)` ratio for it is 1.56 which is greater than 1.5 |
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| 233. |
Isotopes of same elemeents have the same number ofA. ProtonsB. NeutronsC. DeutronsD. None |
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Answer» Correct Answer - A Isotopes of same elements have the same number of protons but different number of neutrons. |
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| 234. |
Which is not emitted by radioactive substanceA. `alpha`-raysB. `beta-`raysC. PositronD. Proton |
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Answer» Correct Answer - D Proton is not emitted by radioactive susbtances. |
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| 235. |
Emission of `beta` -particle by an atom of an element results in the formation of itsA. IsotopeB. IsomerC. IsomorphD. Isobar |
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Answer» Correct Answer - D `._(1)H^(3) rarr ._(2)He^(3) + ._(-1)e^(0)` `._(1)H^(3) and ._(2)He^(3)` are isobars (same mass no.) |
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| 236. |
In a radioactive decay, an emitted electron comes fromA. Nucleus of the atomB. Inner orbital of the atomC. Outermost orbit of the atomD. Orbit having principal quantum number one |
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Answer» Correct Answer - A In nucleus electrons formed by the following decay `._(0)n^(1) rarr ._(+1)p^(1) + ._(-1)e^(0)` |
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| 237. |
Successive emission of an `alpha`-particle and two `beta` -particle by an atom of an element results in the formation of itsA. IsobarB. IsomorphC. IsotopeD. Isome |
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Answer» Correct Answer - C `._(Z)A^(m) rarr ._(z)B^(m-4) + ._(2)He^(4) + 2 ._(-1_e^(0)` |
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| 238. |
Neutrons are more effective projectiles than protons because theyA. Are attracted by the nucleiB. Are not repelled by the nucleiC. Travel with high speedD. None of these |
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Answer» Correct Answer - B `gamma`-particles are neutral, hence they do not get repelled by the electrostatic force of nuclei. |
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| 239. |
In a radioactive decay, an emitted electron comes fromA. the nucleus of atomB. the orbit with principal quantum number 1C. the inner orbital of the atomD. the outermost orbit of the atom |
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Answer» Correct Answer - A When a radioactive leements emits and electron then one neutron in the nucleus change into poroton so atomic number increase by one unit `_(91)Pa^(234)rarr_(94)U^(234)+_(-1)e^(0)` In nucleus the following reaction takes place `_(0)n^(1)rarr_(1)H^(1)_(-1)H^(1)+_(-1)e^(0)` |
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| 240. |
Assertion : Protons are more effective than neutrons of equal energy in causing artifical disintegration of atoms. Reason : Neutrons are neutral they penetrate the nucleus.A. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanantion of the assertionC. If assertion is true but reason is falseD. If assertion is false but reason is true |
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Answer» Correct Answer - D Neutrons are more effective than protons of equal energy in causing artificial disintegration of atoms. Neutrons are neutral they penetrate the nucleus and do not exert any repulsive force like positive charged protons. |
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| 241. |
Assertion : Nuclear fission is always accompanied by release of energy Reason : Nuclear fission is a chain processA. If both assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanantion of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false |
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Answer» Correct Answer - B It is correct that during nuclear fission energy is always released and it is also true that nuclear fission is a chain process |
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| 242. |
The energy equivalent to 1 amu is?A. `931.5 MeV`B. `93.15 MeV`C. `460 MeV`D. `554 MeV` |
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Answer» Correct Answer - A 1 amu `= 931.5 MeV` |
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| 243. |
In nuclear reaction `._(4)Be^(9)+._(2)He^(4)rarr._(6)C^(12)+X,X` will beA. 4B. 9C. 7D. 6 |
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Answer» Correct Answer - B Equate atomic no. and mass no. |
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| 244. |
Breeder reactors are nuclear reactors that are capable of converting non-radioactive isotopes into radioactive fissionable isotopes, which can be used for generating energy, `U-238`, a non-radioactive isotope is thus converted into radioactive.A. `U-234`B. `Pu-94`C. `I-131`D. `C-13` |
| Answer» Correct Answer - B | |
| 245. |
The nuclear radius as compared to the atomic radius, is of the order ofA. `10^(-2)`B. `10^(-15)`C. `10^(-4)`D. `10^(-8)` |
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Answer» Correct Answer - c The nuclear radius is of the order of `10^(-14)` m while that of atom is of the order of `10^(-10)` m. Hence, `("Nuclear radius")/("Atomic radius") = (10^(-14))/(10^(-10)) = 10^(-4)` |
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| 246. |
Which of the following is an example of nuclear fusionA. `._(1)H^(2) + ._(1)H^(2) rarr ._(2)He^(4) +` energyB. `._(92)U^(235) + ._(0)n^(1) rarr ._(56)Ba^(141) + ._(36)Kr^(92) + 3 ._(0)n^(1) +` energyC. `._(13)Al^(27) + ._(1)H^(1) rarr ._(12)Mg^(24) + ._(2) He^(4)`D. None of these |
| Answer» Correct Answer - A | |
| 247. |
What do you understand by the following notatins in respect of the types of artificial transmutation? a. `(n, beta^(ɵ))` b. `(p, beta^(ɵ))` c. `(alpha, n)` d. `(D, p)`A. a. `(n, beta^(ɵ))`B. b. `(p, beta^(ɵ))`C. c. `(alpha, n)`D. d. `(D, p)` |
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Answer» The striking particle is `n` and the particle in the product is `beta^(ɵ)`. b. The strikng particle `p` (proton), the particle produced is `beta^(ɵ)` c.The striking particle is `alpha`-particle `(._(2)He^(4))` and one neutron is on the product side. d. Deutron `(._(1)H^(2))` is the striking particle and one proton is in the product. |
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| 248. |
The carbon dating is based onA. `._(6)^(15)C`B. `._(6)^(14)C`C. `._(6)^(13)C`D. `._(6)^(11)C` |
| Answer» Correct Answer - B | |
| 249. |
For artificial transmutation of nuclei, the most effective one isA. ProtonB. DeuteronC. Helium nucleiD. Neutron |
| Answer» Correct Answer - D | |
| 250. |
After three half lives, the percentage of fraction of amountA. 6.35B. 12.5C. 50D. 75 |
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Answer» Correct Answer - B Given `n = 3`, we know that `N = ((1)/(2))^(n) N_(0)` `:. ((N)/(N_(0))) = ((1)/(3))^(3) = (1)/(8)` or `(N)/(N_(0)) % = (1)/(8) xx 100 = 12.5%` |
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