This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
An element A forms a chloride which contains 29.34% by weight of chloride and is isomorphous with KCl. The molecular weight of A is |
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Answer» `85.49` wt of element = `100-29.34=70.66g` `(W_(1))/(W_(2))=(E_(1))/(E_(2))` `(29.34)/(70.66)=(35.5)/("EQ wt of element")` Ecq wt of element = 85.49 A is isomorphous with KCl so valency of element `A=1` `therefore` at wt of `A=1xx85.49=85.49` |
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| 2. |
An element A crystallises in fcc structure. 200 g of this element has 4.12 xx 10^24 atoms The density of A is 72 cm^(-3). Calculate the edge length of the unit cell. |
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| 3. |
An element A crystallises in fcc structure. 200 g of this element has4.12 xx 10^(24) atoms. The density of A is7.2 " g cm" ^(-3) . Calculate the edge length of the unit cell. |
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Answer» <P> |
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| 4. |
An electronic transition from 1s orbital of an atom causes |
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Answer» ABSORPTION of ENERGY |
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| 5. |
An electron releasing group will not stabilize which of the following groups ? |
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Answer» Carbocation |
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| 6. |
An electron , practically at rest , is initially accelerated through a potential difference of 100 volts . It then has a de Broglie wavelength = lambda_(1) "Å" . It then gets retarded through 19 volts and then has wavelength lambda_(2) "Å" . A further retardation through 32 volts changes the wavelength to lambda_(3) . What is (lambda_(3) - lambda_(2))/(lambda_(1)) ? |
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Answer» `(20)/(41)` |
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| 7. |
An electron of velocity ‘x’ is found to associate with a wave. The velocity to be possessed by the neutron to have half the de-Broglie wavelength possessed by electron is |
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Answer» `X/(1840)` |
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| 8. |
An electron or a proton which one will have a higher velocity to produce matter waves of the same wavelength? Explain it. |
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Answer» Solution :From de-Broglie equation, wavelength `LAMBDA = H/(mv)` for same wavelength with two different particles, (ie) electron and proton `m_1v_1 = m_2v_2` (h is constant) LESSER the MASS of the PARTICLE, greater will be the velocity. Hence electron will have higher velocity. |
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| 9. |
An electron is revolving in the 2^(nd) orbit of He^+ ion. To this if 12.1 eV of energy supplied. Then to which orbit it will be excited. |
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Answer» 6 for `He^+ (Z=2)n=2 thererore E = 0 13.6 eV` SUPPLIED ENERGY = 12.1 eV `=-1.5 eV` (i.e. energy of `6^(th)` orbit) |
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| 10. |
An electron is moving in Bohr's fourth orbit. Its de Broglie wavelength is lambda. What is the circumference of the fourth orbit ? |
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Answer» `(2)/(LAMBDA)` |
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| 11. |
An electron is moving in Bohr's fourth orbit. Its de Broglie wavelength is lambda. What is the circumference of the fourth orbit? |
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Answer» `2// LAMBDA ` |
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| 12. |
An electrons is moving in Bohr's fourth orbits De-Broglie wavelength s lambda.What is the circumference of the fourth orbit? |
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Answer» `LAMBDA` |
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| 13. |
An electron is in a 4f orbital. What possible vales for the quantum, n, l, m and s can it have? |
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Answer» Solution :Since the electron is in a 4F ORBITAL, the value of the principle quantum number, n = 4 For the f-orbital, the SECONDARY quantum number, l = 3 The values of the MAGNETIC quantum (m) are `-l " to " +l` including zero. Therefore, when l = 3, m has seven values, i.e., `-3, -2, -1, 0, +1, +2, and 3` For each value of m, the spin quantum number, s has two values, i.e., `s = +1//2 and s = -1//2` |
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| 14. |
An electron is in one of the 3d orbitals. Give the possible values of n, l and m_(l) for this electron. |
| Answer» SOLUTION :For 3D ORBITAL, `n=3, L=2`. For `l=2, m_(l)=-2-1, 0+1+2`. | |
| 15. |
An electron is allowed to move freely in a closed cubic box of length of side 10 cm. The uncertainty in its velocity will be : |
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Answer» a. `3.35xx10^(-4) m "sec"^(-1)` |
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| 16. |
An electron in the hydrogen atom absorbs energy and jumps to the 4th orbit. Then it jumps back to the ground state in steps, i.e., from 4th to 3rd orbit, then from 3rd to 2nd orbit and finally to the ground state. If a_(0) represents the Bohr radius, the de Broglie wavelength of the electron when it moves in the 3rd orbit after absorbing some definite amount of energy will be |
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Answer» `a_(0)//3` `:. lamda = (2pir)/(n)`. But `r_(3) = a_(0) xx 3^(2) = 9 a_(0)` `:. lamda = (2pi)/(3) xx 9a_(0) = 6pi a_(0)` |
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| 17. |
An electron in the hydrogen atom absorbs energy and jumps to the 4th orbit. Then it jumps back to the ground state in steps, i.e., from 4th to 3rd orbit, then from 3rd to 2nd orbit and finally to the ground state. If the ionization potential of the hydrogen atom in the ground state is 13.6 eV, the longest wavelength of the radiation required to remove the electron from Bohr's first orbit will be approximately |
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Answer» `612 Å` `=21.78 xx 10^(-19) J` `E = hv = (hc)/(lamda)` `:. lamda = (hc)/(E) = ((6.626 xx 10^(-34) Js) (3 xx 10^(8) ms^(-1)))/(21.78 xx 10^(-19) J)` `= 9.12 xx 10^(-8) m = 912 Å` |
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| 18. |
An electron in the hydrogen atom absorbs energy and jumps to the 4th orbit. Then it jumps back to the ground state in steps, i.e., from 4th to 3rd orbit, then from 3rd to 2nd orbit and finally to the ground state. If lamda_(1) is the wavelength of the line for jump of the electron from 4th to 3rd orbit and lamda_(2) that of the line for jump from 3rd to 2nd orbit, then wavelength of the line for the jump from 4th orbit to 2nd orbit will be |
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Answer» `lamda_(1) + lamda_(2)` `bar(v)_(2) = (1)/(lamda_(2)) = R ((1)/(2^(2)) - (1)/(3^(2)))` `bar(v) = (1)/(lamda) = R ((1)/(2^(2)) - (1)/(4^(2)))` Hence, `(1)/(lamda) = (1)/(lamda_(1)) + (1)/(lamda_(2)) = (lamda_(1) + lamda_(2))/(lamda_(1) lamda_(2)) or lamda = (lamda_(1) lamda_(2))/(lamda_(1) + lamda_(2))` |
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| 19. |
An electron in the hydrogen atom absorbs energy and jumps to the 4th orbit. Then it jumps back to the ground state in steps, i.e., from 4th to 3rd orbit, then from 3rd to 2nd orbit and finally to the ground state. The total number of lines produced in the spectrum will be |
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Answer» 3 `SIGMA (n_(2) - n_(1)) = Sigma (4 -1) = Sigma 3 = 3 + 2 + 1 = 6` |
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| 20. |
An electron in Li^(2+) ion is in excited state (n_(2)). The wavelength corresponding to a transition to second orbit is 48.24 nm. From the same orbit, wavelength corresponding to a transition to third orbit is 142.46 nm. The value of n_(2) is: |
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Answer» |
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| 21. |
An electron in the first shell will have ________ stability and _______ energy than an electron in the third shell. |
| Answer» SOLUTION :LARGER , LOWER | |
| 22. |
An electron is in one of the 3dorbitals.Givethe possiblevalues of n , l andm_(l)for thiselectron. |
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Answer» SOLUTION :for 3DORBITAL n= 3 .l =2 So `m_(i) = 2-1 ,-0,+ 1,+2` |
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| 23. |
An electron in an excited state of hydrogen atom absorbs 2.5 times the energy needed to unboundthe electron and moves with a wavelength of 5.416 Å (h = 6.6xx10^(-34) Js) The electron was originally in |
| Answer» Solution :So `e^-` is `2^(ND)` orbit | |
| 24. |
An electron in an excited state of hydrogen atom absorbs 2.5 times the energy needed to unboundthe electron and moves with a wavelength of 5.416 Å (h = 6.6xx10^(-34) Js)The energy absorbed by the electron is |
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Answer» 8.5 eV |
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| 25. |
An electron in an excited state of hydrogen atom absorbs 2.5 times the energy needed to unboundthe electron and moves with a wavelength of 5.416 Å (h = 6.6xx10^(-34) Js) The kinetic energy of the electron is |
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Answer» 3.4 eV |
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| 26. |
An electron in an atom has m = -2 value. Then (I) its 'n' value should be greater thn 2 (II) its 's' value should +1/2 (III) its 'I' value should be 2 (IV) its 'l' value shoul be greater than 1 |
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Answer» I and II are correct |
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| 27. |
An electron in a hydrogen atom in the ground state absorbs energy equal to 1.5 time the minimum energy required to remove the electron from the hydrogen atom. Calculate the wavelength of the electron emitted. |
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Answer» Solution :Energy required to remove electron from ground state of H-atom = 13.6 eV `:.` Energy absorbed by the electron `= 1.5 xx 13.6 eV = 20.4 eV` After the REMOVAL of electron from the atom, extra energy which is converted into kinetic energy `= 20.4 - 13.6 = 6.8 eV` Thus, `(1)/(2) mv^(2) = 6.8 xx 1.602 xx 10^(-19)J` or `v = sqrt((2 xx 6.8 xx 1.602 xx 10^(-19))/(9.11 xx 10^(-31))) = sqrt(2.4 xx 10^(12)) = 1.55 xx 10^(6) MS^(-1)` `lamda = (h)/(mv) = (6.63 xx 10^(-34) KG m^(2) s^(-1))/((9.11 xx 10^(-31) kg) (1.55 xx 10^(6) ms^(-1))) = 4.70 xx 10^(-10) m` |
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| 28. |
An electron in a certain Bohr orbit has velocity 1/275 of the velocity of light. In which orbit the electron is revolving? |
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Answer» SOLUTION :Velocity of ELECTRON `= (1)/(275) xx 3 xx 10^(10) cm s^(-1) = 1.90 xx 10^(8) cm s^(-1)` Velocity of electron in nth orbit of H-like PARTICLES in C.G.S. UNITS is GIVEN by `u_(n) = (2pi Ze^(2))/(nh)` Putting Z = 1 for H and `e = 4.80 xx 10^(-10)" esu"` and `h = 6.626 xx 10^(-27)` erg sec, we get `u_(n) = (2 xx 3.14 xx (4.80 xx 10^(-10))^(2))/(n xx (6.626 xx 10^(-27))) = (2.18 xx 10^(8))/(n)` `:. (2.18 xx 10^(8))/(n) = 1.09 xx 10^(8)` (calculated above) `:. n = 2` |
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| 29. |
An electron having velocity 2xx10^(6)m//s has uncertainty in kineticenergy is (6.66)/pixx10^(-21) J, then calculate the uncretainty in position (in Angstrom ,Å) of the electron .[Given :h=6.60xx10^(-34) J-sec] |
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Answer» SOLUTION :`KE=(1)/(2) mv^(2)""V=2xx10^(6)` `d(KE)=mvdv` `dv=(d(KE))/(mv)""......(1)""But""DELTA"x"=(h)/(4pimDeltav)""....(2)` `Delta"x"=(h)/(4pim(d(KE))/(mv))"" , ""Delta"x"=(6.62xx10^(-34)xx2xx10^(6))/(4pixx6.62/(pi)xx10^(-21))=500Å` |
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| 30. |
An electron has magnetic quantum number as '-3'. Its principal quantum number is |
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Answer» 3 |
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| 31. |
An electron has a speed of 500 ms^(-1) with an uncertainty of 0.02%. What is the uncertainty in locating its position ? [Give mass of electron = 9.1 xx 10^(-31) kg, h = 6.6 xx 10^(-34) J s) |
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| 32. |
An electron from one Bohr stationaryorbitcan goto nexthigherorbit |
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Answer» by emissionof ELECTROMAGNETICRADIATION |
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| 34. |
An electron beam on hitting a ZnS screen produces a scintillation on it. What do you conclude ? |
| Answer» SOLUTION :ELECTRON has PARTICLE NATURE | |
| 35. |
An electron beam can undergo diffraction by crystals. Through what potential should a beam of electrons be accelerated so that its wavelenegth becomes equal to 1.54 Å? |
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Answer» Solution :The aim is to find the energy of the electron in electron volts (eV). As K.E. `= (1)/(2) MV^(2)`, therefore, first we calculate velocity of the electron to have a wavelength of `1.54 Å`. Applying de BROGLIE equation `lamda = (h)/(mv)` `v = (h)/(m XX lamda) = ((6.62 xx 10^(-34) kg m^(2) s^(-1)))/((9.1 xx 10^(-31) kg) (1.54 xx 10^(-10) m)) = 4.72 xx 10^(6) m s^(-1)` Now, K.E. `= (1)/(2) mv^(2) = (1)/(2) (9.1 xx 10^(-31)kg) (4.72 xx 10^(6) ms^(-1))^(2) = 1.01 xx 10^(-17) kg m^(2) s^(-2)` `= 1.01 xx 10^(-17) J " " ( :' 1J = 1 kg m^(2) s^(-2))` `= (1.01 xx 10^(-17))/(1.602 xx 10^(-19)) eV " " ( :' 1 eV = 1.602 xx 10^(-19) J)` `= 63.12 eV` Hence, potential required = 63.12 volts |
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| 36. |
An electron beam after hitting a nickel crystal produces a diffraction pattern ? What do you conclude ? |
| Answer» SOLUTION :ELECTRON has wave-nature | |
| 37. |
An electron, a proton and an alpha particle have kinetic energies of 16E, 4E and E respectively. What is the qualitative order of their de Broglie wavelengths? |
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Answer» `lambda_egt lambda_p = lambda_a` |
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| 38. |
An electric discharge is passed through a mixture containing 50cc of O_(2) and 50cc of H_(2). The volume of the gases formed at 110^(@)C will be |
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Answer» 50cc `(50)/(2)lt(50)/(1)` `implies H_(2)` is the L.R `2ml H_(2)RARR 2ml H_(2)O` `50ml H_(2)rarr50mlH_(2)O` VOLUME of `O_(2)` used = 25ml implies leftover 25ml `THEREFORE` TOTAL volume of gases = `50+25=75ml` |
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| 39. |
An electric current is passed through two voltameters connected in series and containing CuSO_4 and AgNO_3 solutions respectively. The masses of copper and silver deposited are 0.424 g and 1.44 g respectively. Find the equivalent mass of silver if that of copper is 31.75. |
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| 41. |
An azeotropic solution of two liquids has a boiling point lower than either of the boiling points of the two liquids when it. |
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Answer» SHOWS negative DEVIATION |
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| 42. |
An average personneeds about 10,000 kJ per day. How muchcarbohydrates ( in mass) willhe haveto consume, assuming that all his energy needs are met only by carbohydrates in the form glucose ? Given that the heat of combustion of glucoseis 2900 kJ mol^(-1) |
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| 43. |
An automobile antifreeze consist of 38.7% carbon, 9.7% hydrogen and remaining oxygen by weight. When 0.93g of it are vaporised at 200^(@)C and 1 atm pressure, 582 mL of vapour are formed. Find molecular formula of antifreeze. |
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| 44. |
An atomic orbital |
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Answer» defines exactly the POSITION of an electron relative to the nucleus |
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| 45. |
An atomorbitalshas n=3 .What are thepossiblevaluesof l and m_(l) ? |
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Answer» SOLUTION :L=0 ,1,2 so (n-1)equalvalueof l l=0than `m_(l) =0` l=1than `m_(l) = 1 ,0,+1 ` `l=2` than`m_(l)= 2 -1 0,+1+2` Thustotalvalueof `m_(i)= 1+3+5= 9` |
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| 46. |
An atom of radium combines with two atoms of chlorine to formRaCl_(2) molecules . The radioactivity of RaCl_(2) will be |
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Answer» as MUCH as that of same QUANTITY of Ra |
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| 47. |
An atom of an element is 55.847 times as heavier as 1/12 mass of an atom of C^12. What is the atomic mass of the element in amu ? |
| Answer» Solution :Since an atom of the given element is 55.847 TIMES heavier than 1/12 MASS of an atom of `C^(12)`, the atomic mass of the given element, by definition, will be 55.847 amu. | |
| 48. |
An atom of an element contains 35 electrons and 45 neutrons.Deduce(i)the number of protons(ii)the electronic configuration for the element(iii)All the four quantum numbers for the last electron |
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Answer» Solution :An element X contains 35 ELECTRONS 45 electrons (i) The NUMBER of protons must be equal to the number of electrons.So the number of protons=35 (ii)Number of electrons =35 so the ELECTRONIC configuration is `1s^(2)2S^(2)2p^(6)3s^(2)3p^(6)4s^(2)3d^(10)4p^(2)` (iii) The last ELECTRON i.e `5^(h)` electron in 4p orbital has the following quantum numbers. n=4,l=1,m=+1,s=-1/2 |
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| 49. |
An atom of an element contains 35 electrons and 45 neutrons. Deduce. (i) the number of protons (ii) the electronic configuration for the element (iii) All the four quantum numbers for the last electron. |
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Answer» Solution :no. of ELECTRONS : 35 (GIVEN) no. of protons : 35 Electronic configuration `1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4p^5` last electron present in `4p_y` orbital `n = 4 l = 1 m_l = "EITHER" + 1 or -1 and s = -1//2` |
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| 50. |
An atom of an element contains 29 electrons and 35 neutrons. Deduce (i)the number of protons . (ii)the electronic configuration of the element. |
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Answer» Solution :(i) For a neutral atom,NUMBER of ELECTRONS = number of protons 29 electrons = 29 protons. (ii) `29Z = 1s^(2),2s^(2),2p^(6),3s^(2),3p^(6),3d^(10),4S^(1)` (The element is copper). |
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