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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.
| 301. |
In `1894`, Lord Rayleigh reported that the mass of chemically prepared nitrogen was different from that of nitrogen extracted from the atmosphere, as shown in Tables `1` and `2`. Latter, this difference was attributed to the presence of argon in atmospheric nitrogen. The masses of gases were mearsured by using a glass vessel with a known volume under atmospheric pressure `(1.013xx10^(5)Pa)`. `|{:("From nitric oxide",,2.3001 g),("From nitrous oxide",,2.2990 g),("From amonium nitrite purified at a red heat",,2.2987 g),("From urea",,2.2985 g),("From ammonium nitrite purified in the cold",,2.2987 g),("Mean",,2.2990 g):}|` `|{:(O_(2) "was removed by hot copper" (1892),,2.3103 g),(O_(2) "was removed by hot iron" (1893),,2.3100 g),(O_(2) "was removed by ferrous hydrate (1894),2.3102 g,),(Mean,,2.3102 g):}|` Ramsay and cleve discovered helium in cleveite (a mineral consiting of uranium oxide and oxides of lead, thorium, and rare earths, an impure variety of uraninite) independently and virtually simultaneously in `1895`. The gas extracted from the rock showed a unique spectroscopic line at around `588` nm (indicated by `D3` in Figure `1`), which was fist observed in the spectrum of solar prominence during a total eclipse in `1868`, near the well-known `D_(1)` and `D_(2)` lines of sodium. `ul("Which")` equation explains the occurrence of argon in rocks among [A] to [D] below? Mark one. One of the strongest evidences for the monoatomicity of argon and helium is the ratio of the heat capacity under constant pressure to that at constant volume, `gamma=C_(p)//C_(v)`, which is exactly `5//3 (1.67 +- 0.01)` for a monoatomic gas. The ratio was derived from the measurement of speed of sound `v_(s)` by using the following equation, where f and the frequency and wavelength of the sound, and R, T, and M denote the molar gas constant, absolute temperature, and molar mass, respectively. `v_(s)=flambda=sqrt((gammaRT)/(M))` For an unknown gas sample, the wavelength of the sound was measured to be `=0.116m` at a frequency of `f=3520 Hz (Hz =s^(-1))` and temperature of `15.0^(@)C` and under atmospheric pressure `(1.013. 10^(5) Pa)`. The density of the gas for these conditions was measured to be `0.850 +- 0.005 kg m^(-3)`.A. `ArF_(2)" " Ar+F_(2)`B. `ArXe rarr Ar+Xe`C. `^(40)K rarr `^(40)Ar+ epsilon//beta^(+)`` (electron capture//position emission)D. `^(126)I rarr `^(126)Ar+beta^(-)`` |
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Answer» Correct Answer - `[C]` is a well known radioactive decay reaction occurring with a half life of the order of the earth age. No stable compound of Ar, such as `ArF_(2)` or `ArXe`, can be expected Products of `[D]` should be `^(126)Xe+beta^(-)`. The correct answer is `[C]` |
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| 302. |
How can the circulation of blood be tested by using radioisotope? |
| Answer» By injecting a saline solution containing a little radioactive `Na-24` isotope and then detecting its presence in different partsd using a Geiger-Muller counter. | |
| 303. |
How is plutonium obtained? |
| Answer» `._(0)n^(1) + ._(92)U^(238) - gt ._(92)U^(239) underset(-beta)rarr ._(93)Np^(239) underset(-beta)rarr ._(94)Pu^(239)` | |
| 304. |
In a nuclear reactor, heavy water is usedA. to provide high speed neutronsB. to increase the speed of neutronsC. to capture neutrons produced by nuclear fissionD. to transfer the heat from the nuclear reactor |
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Answer» Correct Answer - d |
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| 305. |
What is the role of heavy water in a nuclear reactor? |
| Answer» It acts both as a moderator and a coolant. | |
| 306. |
An atom of radium combines with two atoms of chlorine of form `RaCl_(2)` molecule. The radioactivity of `RaCl_(2)` will beA. ZeroB. `1//3` of the same quantity of radiumC. As much as that of same quantity of radiumD. `1//4` of the same quantity of radium |
| Answer» Correct Answer - C | |
| 307. |
If radium and chlorine combine to form radium chloride the compound isA. No longer radioactiveB. Twice as radioactive as radiumC. Half as radioactive as radiumD. Thrice as radioactive as radium |
| Answer» Correct Answer - D | |
| 308. |
The emission of an `alpha-` particle reduces the mass of nuclei by 4 units and increases its atomic number by 2. |
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Answer» Correct Answer - F |
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| 309. |
A particle having the same charge and 200 times greater mass than that of electron isA. PositronB. ProtonC. NeutrinoD. Meson |
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Answer» Correct Answer - D Meson `(mu)` have 200-300 times mass of electron and +ve, 0 or -ve charges |
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| 310. |
Which of the following is/are not trueA. The most radioactive element present in pitchblende is uraniumB. `P - 32` is used for the treatment of leukaemiaC. `CO_(2)` present in the air contains `C - 12` onlyD. Emission of `gamma`- rays changes the mass number but not atomic number |
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Answer» Correct Answer - A::C::D (a) Is not true because most radioactive element present in pitchblende is Radium. (c) Is not true because `CO_(2)` in the air contains `C - 12` as well as `C - 14` (d) Is not true because emission of `gamma-` rays, neither changes mass number nor atomic number |
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| 311. |
Neutrino hasA. Charge +1, mass 1B. Charge 0, mass 0C. Charge -1, mass 1D. Charge 0, mass 1 |
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Answer» Correct Answer - B Neutrino has no mass and no charge and are thus known as ghost particles |
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| 312. |
The coolant used in the reaction core can beA. Heavy waterB. Molten SodiumC. Alloy of sodium and potassiumD. Molten silver |
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Answer» Correct Answer - A::B::C Except molten silver, all other given susbtances are used as coolants |
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| 313. |
`._(6)C^(14)` in upper atmosphere is generated by the nuclear reactionA. `._(7)N^(14) + ._(1)H^(1) rarr ._(6)C^(14) + ._(+1)e^(0) + ._(1)H^(1)`B. `._(7)N^(14) rarr ._(6)C^(14) + ._(+1)e^(0)`C. `._(7)N^(14) + ._(0)n^(1) rarr ._(6)C^(14) + ._(1)H^(1)`D. `._(7)N^(14) + ._(1)H^(1) rarr ._(6)C^(11) + ._(2)He^(4)` |
| Answer» Correct Answer - C | |
| 314. |
The charge on positron is equal to the charge on which one of the followingA. ProtonB. ElectronC. `alpha-`particlesD. Neutron |
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Answer» Correct Answer - A Charge on positron and proton is about `+ 1.602 x 10^(-19) C` |
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| 315. |
The fertile nuclides among the following areA. `U 238`B. `Th - 232`C. `U - 235`D. `Pu - 239` |
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Answer» Correct Answer - A::B `U - 238` and Th - 232 can be converted into fissionable nuclides. Hence, they are fertile nuclides. `U - 235 and Pu - 239` are fissionable and hence they are fissile nuclides. |
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| 316. |
The nucleus of radioactive element possessesA. Low binding energyB. High binding energyC. Zero binding energyD. High potential energy |
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Answer» Correct Answer - A Low binding energy causes radioactivity |
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| 317. |
The elements which have magic number of protons and neutrons among the following areA. `._(92)^(208)Pb`B. `._(56)^(138)Ba`C. `._(8)^(16)O`D. `._(18)^(38)Ar` |
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Answer» Correct Answer - A::C Magic number are 2, 8, 20, 50, 82 and 126. (a) `n = 126, p = 82` (b) `n = 82, p = 56` (c) `n = 8, p = 8` (d) `n = 20, p = 18` |
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| 318. |
Which of the following `"is"//"are"` incorrect?A. 1 curie `- 3.7 xx 10^(10)` disB. Actinium series starts withs `U^(238)`C. Nuclear isomers contains the same number of protons and neutrons.D. The decay constant is independent of the number of the substance taken. |
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Answer» Correct Answer - C::D Nuclear isomers have same atomic number and atomic mass number. The decay constant depends upon initial amount of substance, `K = (2.303)/(t) "log" (a)/(a - x)` |
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| 319. |
In the reaction, `Pooverset(-alpha)rarr Pb overset(-beta)rarr Bi`, if Bi, belongs to group 15, to which Po belongsA. 14B. 15C. 13D. 16 |
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Answer» Correct Answer - D According to group displacement law |
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| 320. |
Of the following atoms, which one of the highest n/p ratioA. `Ne^(16)`B. `O^(16)`C. `F^(16)`D. `N^(16)` |
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Answer» Correct Answer - D Highest n/p ratio `._(10)Ne^(16) rArr ._(n =6)^(p = 10) (n)/(p) = (6)/(10) = 0.6, ._(8)O^(16) rArr._(n=8)^(p=8) n//p = 1` `._(9)F^(16) rArr._(n =7)^(p =9)(n)/(p) = (7)/(9) = 0.778 ? , N^(16) rArr ._(n =9)^(p = 7)n//p = (9)/(7) = 1.2857` |
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| 321. |
Magic number elements are those isotopes of elementsA. In which the number of protons or neutron is 2,8,20,28,50,82, or 125B. Which are relatively more abundantC. Which are unusually stableD. All of equal |
| Answer» Correct Answer - A | |
| 322. |
Which of the following nuclei are doubly magic?A. `._(92)U^(238)`B. `._(2)He^(4)`C. `._(8)O^(16)`D. `._(82)Pb^(208)` |
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Answer» Correct Answer - B::C::D Both neutron and proton are magic numbers. |
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| 323. |
Which of the following has magic number of neutrons?A. `._(13)Al^(27)`B. `._(83)Bi^(209)`C. `._(92)U^(238)`D. `._(26)Fe^(56)` |
| Answer» Correct Answer - B | |
| 324. |
Nuclear reactivity of Na and `Na^(+)` is same because both haveA. Same electron and protonB. Same proton and same neutronC. Different electron and protonD. Different proton and neutron |
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Answer» Correct Answer - B Nuclear reactivity depends upon the number of protons and neutrons |
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| 325. |
`._(Z)X^(M) + ._(2)He^(4) rarr ._(15)P^(30) + ._(0)n^(1)`. ThenA. `Z = 12, M = 27`B. `Z = 13, M = 27`C. `Z = 12, M = 17`D. `Z = 13, M = 28` |
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Answer» Correct Answer - B Equate atomic no. and mass no. |
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| 326. |
When a radioactive substance is subjected to a vacuum, the rate of disintegration per secondA. Increases considerablyB. Increases only if the products are gaseousC. Suffers a slight decreaseD. |
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Answer» Correct Answer - C Rate of disintegration does not depend upon the environment factor. |
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| 327. |
Gamma rays produce maximum ionization in gases. |
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Answer» Correct Answer - F |
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| 328. |
Which of the following has the highest value of radioactivityA. 1 g of RaB. 1 g of `RaSO_(4)`C. 1 g of `RaBr_(2)`D. 1 g of Ra `(HPO_(4))` |
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Answer» Correct Answer - A Radioactivity follows `1^(st)` order kinetics. So greater the concentration of radioactive nuclide, greater will be the radioactivity. Since 1 g of Ra has maximum number of radioactive nuclides as compared to 1 g `RaSO_(4) or RaBr_(2) or Ra(HPO_(4))`. So it will have the highest value of radioactivity |
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| 329. |
In the first order reaction, the concentration of the reactent is redduced to 25% in one hour. The half life period of the reactiion isA. 2 hrB. 4hrC. 1/2 hrD. 1/4 hr |
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Answer» Correct Answer - c `N=N""_(0)/2""^(n)(n=t/t""_(1//2))` |
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| 330. |
A human body required the 0.01 M activity of radioactive substance after 24 h. Half life of radioactive substance is 6h. Then injection of maximum activity of radioactie substance that can be injected will beA. 0.08B. 0.04C. 0.16D. 0.32 |
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Answer» Correct Answer - C Remaining activity =0.01 M after 24 h Remaining activity =Initial activity `xx(1/2)^(n)` used half life time (n)=`("Total time")/(t_(1//2))=(24)/(6)=4` So, 0.01=Initial activity `xx(1/2)^(4)` Initial activity =`0.01xx16=0=0.16` |
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| 331. |
The decay constant of a radioactive sample is `lambda`. The half-life and mean life of the sample respectively areA. `(1)/(lambda), ("In" 2)/(lambda)`B. `("In" 2)/(lambda), (1)/(lambda)`C. `lambda "In" 2, (1)/(lambda)`D. `(lambda)/("In" 2), (1)/(lambda)` |
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Answer» Correct Answer - b `t_(1//2) = (log_(e)2)/(lambda)` and average life `= (1)/(lambda)` |
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| 332. |
Sometimes, the ejection of an `alpha`-particle does not completely stabilise the nucleus. In such a case, more `alpha`-particles may be emitted. The `alpha`-decayA. raises the `n//p` ratio and is often followed by `beta`-emissionB. lowers the `n//p` ratio and is often followed by positron emissionC. raises the `n//p` ratio and is often followed by neutron emissionD. lower the `n//p` ratio and is often followed by `gamma`-rays emission |
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Answer» Correct Answer - a The `n//p` ratio increases in case of `alpha`-decay while decreases during `beta`-decay. |
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| 333. |
Which is the most stable nucleus among these?A. `._(2)He^(3)`B. `._(11)Na^(24)`C. `._(83)Bi^(210)`D. `._(82)Pb^(207)` |
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Answer» Correct Answer - d `n//p` ratio for `._(2)He^(3) = (1)/(2) = 0.5 (lt1)` `n//p` ratio for `._(11)Na^(24) = (13)/(11) = 1.19` (greater than that of stable isotope `._(11)Na^(23)`) `n//p` ratio for `._(83)Bi^(210) = (127)/(83) = 1.54 (gt 1.53)` `n//p` ratio for `._(82)Pb^(207) = (125)/(82) = 1.53` Hence, `._(82)Pb^(207)` is the most stable as its`n//p` ratio lies between the stability range, i.e., (1.00 - 1.53). |
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| 334. |
Which of the following statement is falseA. In chlorine gas, the ratio of `Cl^(35) and Cl^(37) " is " 1 : 3`B. The hydrogen bomb is based on the principle of nuclear fusionC. The atom bomb is based on the principle of nuclear fissionD. The penetrating power of a proton is less than that of an electron |
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Answer» Correct Answer - A In chlorine gas ratio of `Cl^(35) and Cl^(37) " is " 3 :1` |
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| 335. |
NuclidesA. Have specific atomic numberB. Have same number of protonsC. Have specific atomic number and mass numbersD. Are isotopes |
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Answer» Correct Answer - D The isotopes of an element is represented by writing the symbol of the element and representing the atomic number and mass number as subscript and superscript respectively are called nuclides |
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| 336. |
Which isotope on bombardment with `alpha`-particles will give `._(8)O^(17) and ._(1)H^(1)`A. `._(8)O^(16)`B. `._(7)N^(14)`C. `._(7)N^(15)`D. `._(6)C^(14)` |
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Answer» Correct Answer - B `._(7)N^(14) + ._(2)He^(4) rarr ._(8)O^(17) + ._(1)H^(1)` |
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| 337. |
The radioactive disintegration follows the kinetics ofA. zero orderB. first orderC. second orderD. third order |
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Answer» Correct Answer - b The radioacitve disintegration follows the first order kinetics, for which decay constant is given by `lambda=(2.303)/(t)log(N_(0))/(N)` |
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| 338. |
Several short-lived radioactive species have been used to determine the age of wood or animal fossils. One of the most intresting substance is `""_(6)C""^(14)`(half-life fossils, etc.). Carbon-14 is produced by the bombardment of nitrogen atoms present in the upper atmosphere with neutrons (from cosmic rays). `""_(7)N""^(14)+""_(0)n""^(1)to""_(6)C""^(14)+""_(1)H""_(1)` Thus carbon-14 is oxidised, to `CO""_(2)` and eventually lingested by land animals. The death of plants or animals put an end to the intake of `C""_(14)` from the atmosphere. After this the amount of `C""_(14)` in the dead tissues starts decreasing due to its disintegration as per the following reaction : `""_(6)C""^(14)to""_(7)N""^(14)+""_(-1)beta""^(0)` The `C""^(14)` isotope enters the biosphjere when carbon dioxide is taken up in plant photosynthesis. Plants are eaten by animals, which exhale `C""^(14)` as `CO""_(2)`. Eventually, `C""^(14)` participates in many aspects of carbon cycle. The `C""^(14)` lost by radioactive decay-replenishment process, a dynamic rquillibrium is established whereby the ratio of `C""^(14)` to `C""^(12)` remains constant in living matter. But when an individual plant or an animal dies, the `C""^(14)` isotpe inn it is no longer replenished, so the ratio decreases as `C""^(14)` decays. So, ther number `C""^(14)` nuclei after time t (after the death of living matter) would be less than in a livingthe following formula, `t""_(1//2)=0.693`/? The intensity of the cosmic rays have remain the same for 30,000 years. But since some years changes in this are observed due to excessive burning of fossil fuel and nuclear test? What should be the age of the fossil meaningful determination of its age?A. 6 yearsB. 6000 yearsC. 60000 yearsD. can be used to determine any age |
| Answer» Correct Answer - a | |
| 339. |
Half-life of radius is 1580 yr. Its average life will beA. `2.5 xx 10^(3) yr`B. `1.832 xx 10^(3) yr`C. `2.275 xx 10^(3) yr`D. `8.825xx 10^(2) yr` |
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Answer» Correct Answer - C Average life period `= 1.44 xx t_(1//2)` `1.44 xx 1580 = 2275.2 = 2.275 xx 10^(3) yr` |
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| 340. |
The equation `._(3)Li^(6) + ._(1)H^(2) rarr 2 ._(2)He^(4) +` energy representsA. Synthesis of heliumB. Transmutation of elementC. Fusion reactionD. Nuclear fission |
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Answer» Correct Answer - C Joining up of two lighter nuclei is fusion |
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| 341. |
`U^(235) + n^(1)rarr` fission product + neutron + 3.2`xx 10^(-11)j`. The energy released , when 1g of `u^(235)` finally undergoes fission , isA. `12.75xx10^(8)kj`B. `18.60xx10^(9)kj`C. `8.21xx10^(7)kj`D. `6.55xx10^(6)kj` |
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Answer» Correct Answer - C 235 g of u-235 contains `6.023xx10^(23)` atoms 1g u-235=`(6.023xx10^(23))/(235)atoms` `therefore` Energy relaeased =`(3.2xx10^(-11)xx6.023xx10^(23))/(235)j` `=8.21xx10^(10)j` `8.21xx10^(7) kj` |
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| 342. |
The reaction `._(1)H^(2) + ._(1)H^(3) rarr ._(2)He^(4) + ._(0)n^(1)+` energy representsA. Nuclear fissionB. Nuclear fusionC. Artifical disintegrationD. Transmutation of element |
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Answer» Correct Answer - B In hydrogen bomb, the following reaction occurs, `._(1)H^(2) + ._(1)H^(3) rarr ._(2)He^(4) + ._(0)^(1) n +` energy |
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| 343. |
The modern basis of atomic weight isA. Isotope `H^(1) = 1.000`B. Oxygen `= 16.000`C. Isotope `O^(16) = 16.000`D. Isotope `C^(12) = 12.000` |
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Answer» Correct Answer - D Isotope `C^(12)` is the modern basis of atomic weight. |
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| 344. |
The rate of disintegration of a radioactive substance is `……………………………` to the number of atoms present at that time . |
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Answer» Correct Answer - Directly proportional |
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| 345. |
When a slow neutron goes sufficiently close to a `U^(235)` nucleus, then the process which takes place isA. Fusion of `U^(235)`B. Fission of `U^(235)`C. Fusion of neutronD. First (a) then (b) |
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Answer» Correct Answer - B The splitting of a heavier atom like that of `U - 235` into a number of fragments of much smaller mass by sutiable bombardment with sub-atomic particles with liberation of huge amount of energy is called nuclear fission |
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| 346. |
When a radioactive substance is subjected to vacuum, the rate of disintegration per secondA. Increases considerablyB. Increases only if the products are gaseousC. Is not affectedD. Suffers a slight decrease |
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Answer» Correct Answer - C Rate of disintegration is not affected by environmental conditions |
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| 347. |
In nuclear reactors heavy water is used as aA. FuelB. ProhectileC. ModeratordD. Arrester |
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Answer» Correct Answer - C Heavy water `(D_(2)O)` works a moderator to slow down the speed of neutron. |
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| 348. |
A substance used as a moderator in nuclear reactors isA. CadminumB. Uranium-235C. LeadD. Heavy water |
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Answer» Correct Answer - D Heavy water `(D_(2)O)` is used as a moderator in nuclear reactor |
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| 349. |
A possible material for use in the nuclear reactors as a fuel isA. ThoriumB. ZirconiumC. BerylliumD. Plutonium |
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Answer» Correct Answer - D Uranium or Plutonium is atomic fuel |
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| 350. |
Radioactive isotope of hydrogen isA. TritiumB. DeuteriumC. Para hydrogenD. Ortho hydrogen |
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Answer» Correct Answer - A `._(1)H^(3) rarr._(2)He^(3) + ._(-1)e^(0)` |
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