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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.
| 251. |
Ionization energy of a hydrogen-like ion A is greater than that of another hydrogen like ion B . Let r, u, E and L represent the radius of the orbit , speed of the electron , total energy of the electron and angular momentum of the electron respectively (for the same n ). In ground state :A. `r_(A) gt r_(B)`B. `u_(A) gt u_(B)`C. `E_(A) lt E_(B)`D. `L_(A) gt L_(B)` |
| Answer» Correct Answer - B | |
| 252. |
The radius of the atom is of the order ofA. `10^(-8)m`B. `10^(-9)m`C. `10^(-11)m`D. `10^(-10)m` |
| Answer» Correct Answer - D | |
| 253. |
According to classical theory, the circular path of an electron in Rutherford atom isA. parabolicB. hyperboicC. cicularD. elliiptical |
| Answer» Correct Answer - B | |
| 254. |
(A) in alpha particle scattering number of alpha paritcle undergoing head on collision is small. (R) small fraction of the number of incident particles rebound back.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 is not the correct explanation of assertion.C. if assertion is true but reason is false.D. if both assertion and reason are false. |
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Answer» Correct Answer - B the number of alpha particles undergoing head on collision is small. This in turn, imlies that the mass of the atom is concentrated in a small volume. |
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| 255. |
What should be the effect of impact parameter upon the deviation of `alpha`-particle. |
| Answer» As the impact parameter decreases, electrostatic force of repulsion and therefore deviation will increase. | |
| 256. |
What was the fraction of `alpha`-particles in which deflection of more than `90^@` was observed ? |
| Answer» Correct Answer - `0.0125%` | |
| 257. |
What should be the angle of deviation for (i)b=0 , (ii)a large value of b |
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Answer» (i)`theta=180^@` (ii)`theta=0^@` (undeviated) |
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| 258. |
If the radius of inner most electronic orbit of a hydrogen atom is `5.3xx10^(-11)` m, then the radii of `n=2` orbit isA. `1.12 Å`B. `2.12 Å`C. `3.22 Å`D. `4.54 Å` |
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Answer» Correct Answer - B As,`r_n=n^2a_0` Here,`a_0=5.3xx10^(-11)m`,`n=2` `therefore r_2=(2)^2a_0=4a_0=4xx5.3xx10^(-11)m` `=21.2xx10^(-11)m=2.12Å`. |
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| 259. |
The linear momentum of an electron in a Bohr orbit of an H-atom (principal quantum number n) is proportional to(A) \(\cfrac1{n^2}\)(B) \(\cfrac1n\)(C) n (D) n2. |
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Answer» Correct option is (B) \(\cfrac1n\) |
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| 260. |
What was the fraction of `alpha`-particles in which deflection of more than `1^@` was observed ? |
| Answer» Correct Answer - `0.14%` | |
| 261. |
What would be the charge in tangential velocity of an electron, if it remains in same orbit and electronic charge is doubled ? |
| Answer» `v prop sqrte` therefore , tangential velocity become `sqrt2v` | |
| 262. |
The radius of the first Bohr orbit is 0.53 Å and that of nth orbit is 212 Å. The value of n is (A) 2 (B) 12 (C) 20 (D) 400. |
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Answer» Correct option is (C) 20 |
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| 263. |
In the question number 59, the value of velocity of the revolving electron isA. `1.2xx10^6ms^(-1)`B. `2.2xx10^6ms^(-1)`C. `3.2xx10^6ms^(-1)`D. `4.2xx10^6ms^(-1)` |
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Answer» Correct Answer - B As `v=(e)/(sqrt(4piepsilon_0mr))` Here, `e=1.6xx10^(-19)C,m=9.1xx10^(-31)kg,r=5.3xx10^(-11)m` and `4piepsilon_0=(1)/(9xx10^(9))N^(-1)m^(-2)C^(2)` `therefore v=(1.6xx10^(-19))/sqrt((1)/(9xx10^(9))xx9.1xx10^(-31)xx5.3xx10^(-11))` `=2.2xx10^6ms^(-1)`. |
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| 264. |
Using Bohr model, calculate the electric current created by the electron when the H-atom is in the ground state. |
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Answer» The electron in Hydrogen atom in ground state revolves on a circular path whose radius is equal to the Bohr radius `(a_(n))` Let the velocity of electron is v. `:.` Number of revolutions per unit time `= (2pia_(0))/(v)` The electric current is given by `i = ( q)/(t)`, if q change flows in time `t`. Here , `q = e` The electric current is given by `i = (2pia_(0))/(v)e`. |
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| 265. |
Give the two ways of classification of matter. |
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Answer» There are two ways of classification of matter. 1. According to physical state as solid, liquid or gas. 2. According to its composition as element, compound or mixture. |
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| 266. |
Explain the conservation of mass. |
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Answer» Antoine L. Lavoisier, a French scientist, established the theory of Law of Conservation of Mass. The law of conservation of mass states, “Mass can neither be created nor destroyed in a chemical reaction”. All matters in the universe exist in three states. There are two ways of classification of matter. 1. According to physical state as solid, liquid or gas. 2. According to its composition as element, compound or mixture. According to this law mass of an isolated system will remain constant over time. This means when mass is enclosed in a system and none is allowed in or out, its quantity will never change. That is mass will be conserved, and hence this is called Law of Conservation of Mass. This means total mass of products is always equal to the total mass of reactants. As there is no loss of mass of substances, i.e. mass is conserved, that’s why Lavoisier called this the law of conservation of mass. |
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| 267. |
What is the percentage of calcium in calcium carbonate `(CaCO_(3))` ? |
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Answer» Molecular mass of `CaCO_(3) = 40 + 12 + 3 xx 16 = 100 ` amu . Mass of calcium in 1 mol of `CaCO_(3) = 40`g `therefore` percentage of calcium = `(40 xx 100)/(100) = 40` . |
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| 268. |
Calculate the number of calcium ions in 5.6 g of calcium oxice . (Ca = 40) |
| Answer» `6.022 xx 10^(22) g` | |
| 269. |
X-rays were discovered byA. BecqueralB. RoentgenC. Marrie CurieD. Von Laue |
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Answer» Correct Answer - B X-rays were discovered by Roentagen. |
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| 270. |
Which of the following wavelength falls in X - ray regionA. `10000Å`B. `1000Å`C. `1Å`D. `10^(-2)Å` |
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Answer» Correct Answer - C X-rays are electromagnetic waves of wavelength ranging from 0.1 to 100Å` |
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| 271. |
X-rays are in nature similar toA. beta raysB. gamma raysC. de-BroglieD. cathode rays |
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Answer» Correct Answer - B Both X-rays amd gamma rays are electromegnetic in nature. |
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| 272. |
The nature of X-rays spectrum isA. continuousB. lineC. continuous and lineD. None of these |
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Answer» Correct Answer - C In X-rays tube, when high speed electrons strike the target they penetrate to target. They loss their kinetic energy and come to rest inside the metal. The electron before finally being stopped makes several collision with the atom in the target. At each collision one of the following two types of X-rays get formed (i) continuous X-rays (ii) characteristic X-rays. |
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| 273. |
The kinetic energy of electrons that strike the target is increased , then the cut-off wavelength of continuous X-rays spectrumA. increasesB. decreasesC. no changeD. cannot be said |
| Answer» Correct Answer - B | |
| 274. |
If `V` be the accelerating voltage, then the maximum frequency of continuous X-rays is given byA. `(eh)/(V)`B. `(hV)/(e)`C. `(eV)/(h)`D. `(h)/(eV)` |
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Answer» Correct Answer - C Energy , `E=eV=hv_("max")` `:. " " v_("max")=(ev)/(h)` |
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| 275. |
Wavelength of X-ray photon is a and momentum of X-ray photon is b. Now, match the following two columns |
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Answer» Correct Answer - (A`to` q,Btor,Ctop,Dtos) Momentum is given `p=(h)/(lambda) or p prop(1)/(lambda)` Here, wavelength of X-ray photon =a momentum of X-ray photon =b `lambda_(y-"rays")ltlambda_(X-"rays")ltlambda_(UV-"rays")` |
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| 276. |
In the nth orbit, the energy of an electron `E_(n)= -( 13.6)/(n^(2)) eV` for hydrogen atom. The energy rquired to take the electron from first orbit to second orbit will beA. `10. 2 eV`B. `12.1 eV`C. `13.6 eV`D. `3.4 eV` |
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Answer» Correct Answer - A For n=2, using, `E_(n)=(-13.6eV)/(n^(2))E_(2)=-(13.6)/((2)^(2))=-3.4 eV` For n=1,`E_(1)=-13.6 eV` `:. " " E_(1rarr2)=-3.4-(-13.6)=10.2ev` |
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| 277. |
Ground state energy of hydrogen atom is `E_(0)` . Match the following two columns. |
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Answer» Correct Answer - (A `to` r,Btop,Ctyoq,D-q) As `Eprop(Z^(2))/(n^(2))` `:. U=2E,K=-E` |
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| 278. |
In Column I physical quantities corresponding to hydrogen and hydrogen like atom are given. In column II, powers of principal quantum number n are givem on which thosee physical quantities depend. Match the two columns. |
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Answer» Correct Answer - (A`to` r,Btop,ctoq,D-s) `(A) omega=(v)/(r)prop((1//n))/((n^(2)))propn^(-3)` (B) `a=r omega^(2)prop(n^(2))(n^(-6))propn^(-4)` (C) `L=n(h)/(2pi)or Lpropn` (D) `I=mr^(2)or I prop r^(2)prop(n^(2))^(2)propn^(4)` |
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| 279. |
Assertio Wavelength of charachteristic X-rays is given by `(1)/(lambda)prop((1)/(n_(1)^(2))-(1)/(n_(2)^(2)))` in trasnition from ` n_(2) to n_(1)` . In the abvoe relation proportionality constant is series dependent. For different series (K-series, L-series, etc. ) value of this constant will be different. Reason For L-series value of this constant is less than the value for K-seriesA. If both Assertion and Reason ar true and Reason is the correct explanation of Assertion.B. If both Assertion and Reason are true but Reason is not correct explanation of AssertionC. If Assertion is true by Reason is false.D. If Assertion is false but Reason is true. |
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Answer» Correct Answer - C This proportionality constant `prop(Z-b)^(2)` For K-series : b=1 For L-series : b=7.4 |
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| 280. |
Assertion Wavelength of characteristic X-rays is given by `(1)/(lambda)prop((1)/(n_(1)^(2))-(1)/(n_(2)^(2)))` in the transition from `n_(2) to n_(2)` . In the above relation propotionally constant does not deped upon the traget material. Reason Continuous X-rays are target independent.A. If both Assertion and Reason ar true and Reason is the correct explanation of Assertion.B. If both Assertion and Reason are true but Reason is not correct explanation of AssertionC. If Assertion is true by Reason is false.D. If Assertion is false but Reason is true. |
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Answer» Correct Answer - B Proportionality constant `prop(Z-b)^(2)` |
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| 281. |
In a hypotherical Bohr hydrogen, the mass of the electron is doubled. The energy `E_(0)` and the radius `r_(0)` of the first orbit will be (`a_(0)` is the Bohr radius)A. `E_(0)=-27.eV, r_(0)=a_(0)//2`B. `E_(0)=-27.2 eV, r_(0)=a_(0)=a_(0)`C. `E_(0)=-13.6eV, r_(0)=a_(0)//2`D. `E_(0)=-13.6 eV r_(0)=a_(0)` |
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Answer» Correct Answer - A `E prop m " " and " " rprop(1)/(m)` i.e., energy will becomes two times and radius will become half. |
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| 282. |
Consider the following two statements A and B and identify the correct choice in the given answer A : The characteristic X-ray spectrum depends on the nature of the material of the target B : The short wavelength limit of continuous X-ray spectrum varies inversely with the potential difference applied to the X-rays tubeA. A is true and B is falseB. A is false and B are trueC. Both A and B are trueD. Both A and B are false |
| Answer» Correct Answer - C | |
| 283. |
Assertion Energy of characteristic X-rays in more than the energy of continuous X-rays Reason Charactersitic X-rays are produced due to transition of electrons from higher energy states to lower energy states.A. If both Assertion and Reason ar true and Reason is the correct explanation of Assertion.B. If both Assertion and Reason are true but Reason is not correct explanation of AssertionC. If Assertion is true by Reason is false.D. If Assertion is false but Reason is true. |
| Answer» Correct Answer - D | |
| 284. |
For characteristic `X` - ray of some materialA. `E(K_(gamma))ltE(K_(beta))ltE(K_(alpha))`B. `E(K_(alpha))ltE(L_(alpha))ltE(M_(alpha))`C. `lambda(K_(gamma))ltlambda(K_(beta))ltlambda(K_(alpha))`D. `lambda(M_(alpha))ltlambda(L_(alpha))lt lambda (K_(alpha))` |
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Answer» Correct Answer - C As, `E(K_(gamma))gtE(K_(beta))gtE(K_(alpha))` `rArr" " lambda(K_(gamma))ltlambda(K_(beta))ltlambda(K_(alpha))" " [:. Lambdaprop(1)/(E)]` |
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| 285. |
`X`-rays are produced by jumping of:A. electrons from lower to higher energy orbit of atomB. electrons from higher to lower energy orbit of atomC. protons from lower to higher energy orbit of nucleusD. protons from higher to lower energy orbit of nucleus |
| Answer» Correct Answer - B | |
| 286. |
Sharp peak point A represents A. characteristic X-raysB. continuous X-raysC. BremesstrahlungD. discontinuous sepectrum |
| Answer» Correct Answer - A | |
| 287. |
X-ray beam can be deflectedA. magnetic fieldB. electric fieldC. Both (a) and (b)D. None of these |
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Answer» Correct Answer - D d X-rays are electromagnetic waves in nature and they are not deflected by electric and magnetic fields. |
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| 288. |
If the current in the circuit for heating the filament is increased, the cutoff wavelengthA. will increaseB. will decreaseC. will remain unchangedD. may increase of decrease |
| Answer» Correct Answer - C | |
| 289. |
Increase in which of the following increases the penetrating power of the X-rays ?A. velocityB. intensityC. frequencyD. wavelength |
| Answer» Correct Answer - C | |
| 290. |
An X-ray tube is operated at 50 kV. The minimum wavelength produced isA. `0.5Å`B. `0.5Å`C. `0.25Å`D. `1Å` |
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Answer» Correct Answer - C Minimum eavelength produced `lambda_("min")=(12375)/(50xx10^(3))Å=0.240.25Å` |
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| 291. |
`X`-rays are not used for radar purooses, because they are not,A. they are not relfected by the targetB. they are not electromagnetic wavesC. they are completely absorbed by the airD. they sometimes damage the target |
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Answer» Correct Answer - A When X-rays fall on a target, they are absorbed by the target, and they are not reflected by the target, so they are not used for radar purpose. |
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| 292. |
In an `X` - rays tube , the intensity of the emitted `X` - rays beam is increased byA. increasing the filment currentB. decreasing the filment currentC. increasing the target potentialD. decreasing the target potential |
| Answer» Correct Answer - A | |
| 293. |
Hydrogen atom does not emit X-rays becauseA. its energy levels are too close to each otherB. its energy levels ar too far apartC. it has a very small massD. it has a single electron |
| Answer» Correct Answer - A | |
| 294. |
The X- rays beam coming from an X- rays tube will beA. monochromaticB. having all wavelength larger than a certain minimum wavelengthC. having alll wavelengths smaller than a certain maximum wavelenthD. having all wavelength between a minimum and a maximum wavelength |
| Answer» Correct Answer - D | |
| 295. |
X-rays are being produced in a tube operating at `10^(5)V.` The velocity of X-rays produced isA. `3xx10^(8) ms^(-1)`B. `2.8xx10^(8) ms^(-1)`C. `3.1xx10^(8) ms^(-1)`D. `3xx10^(10) ms^(-1)` |
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Answer» Correct Answer - A X-rays travel in straight line with speed of light i.e., `3xx10^(8)m//s.` |
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| 296. |
Consider a photon of continuous X-ray coming from a Coolidge tube. Its energy comes fromA. the kinetic energy of the striking electronB. the kinetic energy of the free electrons of the targetC. the kinetic energy of the ions of the targetD. an atomic transition in the target |
| Answer» Correct Answer - A | |
| 297. |
The energy of a photon of characteristic X-ray from a Coolidge tube comes fromA. the kinetic energy of the striking electronB. the kinetic energy of the free electrons of the targetC. the kinetic energy of the ions of the targetD. an atomic transition in the target |
| Answer» Correct Answer - D | |
| 298. |
Calculate the ionisation potential of a single ionised He-atom. |
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Answer» Correct Answer - 54.3 V approx. |
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| 299. |
The radius of `n^th` orbit `r_n` in the terms of Bohr radius `(a_0)` for a hydrogen atom is given by the relationA. `na_0`B. `sqrt(na_0)`C. `n^2a_0`D. `n^3a_0` |
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Answer» Correct Answer - C The radius of `n^th` orbit `r_n=n^2(ħ^(2)4piepsilon_0)/(me^2)=a_0` (bohr radius) Hence, `r_n=n^2a_0`. |
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| 300. |
In a hydrogen atom, the radius of `n^(th)` bohr orbit is `r_n`. The graph between log `(r_n//r_1)` and logn will beA. B. C. D. |
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Answer» Correct Answer - A we know that `r_npropn^2` or `(r_n//r_1)=n^2` So, log `(r_n//r_1)=21`ogn Hence, the graph between log `(r_n//r_1)` and logn will be a straight line passing through origin. The positive slope is given by `tantheta=2`. |
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