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TEXTBOOK (MCQs)

 

Q(1). For which species Bohr’s theory does not apply

(a) H                             (b) He+

(c) Li2+                          (d) Be

 

Correct Answer: (d) Be

Explanation:

Bohr’s theory is successfully applied to mono-electron system e.g. H, He+, Li2+. However, it fails for multi-electron systems. e.g. Be, since it contains 4 electrons.


Q(2). From the discharge tube experiment, it is concluded that

(a) Mass of proton is in fraction.

(b) Matter contained electrons.

(c) Nucleus contains positive change.

(d) Positive rays are heavier than protons.

 

Correct Answer: (b) Matter contained electrons

Explanation:

In discharge tube experiments, cathode rays were produced. These were proved to be electrons.


Q(3). When an electron of charge ‘e’ and mass ‘m’ moves with velocity ‘v’ about the nuclear change Ze in the circular orbit of radius ‘r’, the P.E of electron is given by

(a) Ze2/r                       (b) – Ze2/r

(c) Ze2/r2                      (d) mv2/r

 

Correct Answer: (b) –Ze2/r

Explanation:

The P.E. of electron is obtained from Columb’s law. Thus it is given as


Q(4). Which of following tells about shells of an atom?

(a) Principal quantum number, n

(b) Azimuthal quantum number, l

(c) Magnetic quantum number, m

(d) Spin quantum number, s

 

Correct Answer: (d) Spin quantum number, s

Explanation:

Three quantum numbers are obtained by solving Schrodinger’s wave equation:

1. Principal quantum number (n)

2. Azimuthal quantum number ()

3. Magnetic quantum number (m)


Q(5). Electronic configuration of species M2+ is 1s2  2s2  2p6  3s2  3p6  3d6 and its atomic weight is 56 number of neutrons in the nucleus of species M is

(a) 20                           (b) 26

(c) 28                           (d) 30

 

Correct Answer: (d) 30

Explanation:

M2+ = 1s2  2s2  2p6  3s2  3p6  3d6

When two electron are added to M2+, it becomes M. the electronic configuration of M is

M = 1s2  2s2  2p6  3s2  3p6  3d8

Thus the atomic number of M is 26 and its atomic mass is 56.

Number of neutrons = 56-26 = 30


Q(6). The energy of an electromagnetic radiation is 3 x 10-12 ergs. What is its wave length in Nano-meters?

(a) 400                        (b) 228.3

(c) 3000                      (d) 662.5

 

Correct Answer: (d) 662.5

Explanation:

Since   107 erg = 1 J

So        3 x 10-12 erg = 3 x 10‑ J

 

 

 

 

            Since 10-9m = 1nm


Q(7). Which of the following configuration is not correct according to Hund’s rule?

(a)         (b)

(c)      (d)

 

Correct Answer:        (b)

Explanation:

According to Hund’s Rule:

If orbitals of same energy are available then electrons will go in separate orbitals with same spin, rather than in same orbital with opposite spin. The correct electronic configuration is


Q(8). Which one of the following statement is not correct?

(a) Rydberg’s constant and wave number have same unit.

(b) Lyman series of hydrogen spectrum occurs in the ultraviolet region.

(c) The angular movement of the electron in the ground state of hydrogen atom is equal to

(d) The radius of first Bohr orbit of hydrogen atom is 2.116 x 10-8cm.

 

Correct Answer: (d) The radius of first Bohr orbit of hydrogen atom is 2.116 x 10-8cm.

Explanation:

Options (a), (b) and (c) are correct.

Option (d) is not correct, since

           

          When n = 1

           


Q(9). Which one of the following is not isoelectronic pair?

(a) Mg2+, Be2+               (b) N3-, O2-

(c) N3-, F                     (d) F, Ai3+

 

Correct Answer: (d) Mg2+, Be2+

Explanation:

The species which contain same number of electrons are called isoelectronic species.

(a) Mg2+ contains 10 electrons but Be2+ contains 2 electrons (not isoelectronic).

(b) Both N3- and O2- contain 10 electrons each (isoelectronic)

(c) Both N3+ and F contain 10 electrons each (isoelectronic)

(d) Both F and Ai3+ contain 10 electrons each (isoelectronic)


Q(10). The third line in Balmer series corresponds to an electronic transfer between which Bohr’s orbits in hydrogen.

(a)                       (b)

(c)                       (d)

 

Correct Answer: (d)

Explanation:

Third line in Balmer series appears when electron jumps from n=5 to n=2 orbit in hydrogen.


 

 

IMPORTANT (MCQs) FOR ECAT & MCAT

 

Q(1). In atomic particles

(a) Mass of neutron is almost equal to mass of electron

(b) e/m of a proton is almost equal to e/m of electron

(c) mass of proton is almost equal to mass of electron

(d) charge of proton is almost equal to charge of electron

 

Correct Answer: (d) correct


Q(2). In discharge tube experiment the pressure of gas was measured at

(a) 760 torr                 (b) 0.1 torr

(c) 0.01 torr                (d) 10 torr

 

Correct Answer: (d) correct


Q(3). The charge (in coulombs) of one gram of electron is

(a) 1.7588 x 10-11          (b) 1.7588 x 1011

(c) 1.602 x 10-19           (d) 1.7588 x 108

 

Correct Answer: (d) correct


Q(4). The nature of cathode rays in discharge tube

(a) Depends on the nature of gas taken in the discharge tube

(b) Depends upon the nature of cathode in discharge tube

(c) Is independent of the nature of the gas in discharge tube

(d) Depends upon the nature of anode in the discharge tube

 

Correct Answer: (d) correct


Q(5). If the e/m value of electron is 1.7588 x 1011 coulombs kg-1, then what would be the mass of electron in grams (charge on electron is 1.6022 x 10-19 coulombs)?

(a) 9.1095 x 1031g        (b) 91.095 x 10-31g

(c) 9.1095 x 10-28g      (d) 0.919095 x 10-33g

 

Correct Answer: (d) correct


Q(6). Negative charge on cathode rays was established by

(a) William Crook       (b) J Perin

(c) J.J. Thomson          (d) Hittrof

 

Correct Answer: (d) correct


Q(7). Cathode rays cause a chemical change because they have __________ effect.

(a) Oxidizing               (b) Conducting

(c) Reducing               (d) Diffusing

 

Correct Answer: (d) correct


Q(8). Mass of electron is

(a) 9.1095 x 1031kg      (b) 9.1095 x 10-31kg

(c) 9.1095 x 10-27kg     (d) 9.1095 x 10-31g

 

Correct Answer: (d) correct

Q(9). The charge on electron was determined by

(a) Bohr                       (b) Rutherford

(c) Millikan                  (d) J.J. Thomson

 

Correct Answer: (d) correct

Q(10). The e/m value for the positive rays is maximum for

(a) Hydrogen              (b) Helium

(c) Nitrogen                (d) Oxygen

 

Correct Answer: (d) correct

Q(11). The e/m of positive rays is __________ than that of cathode rays

(a) equal to                 (b) lesser

(c) greater                   (d) not known

 

Correct Answer: (d) correct

Q(12). Positive rays were discovered by

(a) J.J Thomson           (b) Rutherford

(c) William Crooks      (d) Eugene Gold Stein

 

Correct Answer: (d) correct

Q(13). The positive particle produced in the discharge tube from Hydrogen gas was named Proton by

(a) Millikan                  (b) Goldstein

(c) Rutherford             (d) Chadwick

 

Correct Answer: (d) correct

Q(14). The nature of anode rays depend on

(a) The nature of the electrode

(b) The nature of the residual gas

(c) The nature of the discharge tube

(d) All of above

 

Correct Answer:        (d) correct

Q(15). The nature of positive rays depends on

(a) The nature of electrode

(b) the nature of the discharge tube

(c) the nature of the residual gas

(d) All of the above

 

Correct Answer:        (d) correct

Q(16). Which of the following statement regarding cathode ray is correct

(a) Cathode rays can ionize gas

(b) Cathode rays can possess momentum

(c) Cathode rays can cause chemical changes

(d) All of these

 

Correct Answer:        (d) correct

Q(17). Neutron was discovered by Chadwick in

(a) 1935                        (b) 1930

(c) 1932                        (d) 1934

 

Correct Answer:        (d) correct

Q(18). Bombardment of  on Beryllium (Be) atom emits neutron and this process is called

(a) Natural radioactivity

(b) Artificial radioactivity

(c) Paull exclusion principle

(d) Hund’s rule

 

Correct Answer:        (d) correct

Q(19). . What is “x”?

(a) neutron                 (b) proton

(c) Beta rays                (d) gamma rays

 

Correct Answer:        (d) correct

Q(20). In atomic particles

(a) Mass of neutron is almost equal to mass of electron

(b) e/m of a proton is almost equal to e/m of electron

(c) Mass of proton is almost equal to mass of electron

(d) Charge of proton is almost equal to charge of electron

 

Correct Answer:        (d) correct

Q(21). Rutherford’s model of atom failed because

(a) The atom did not have a nucleus and electron

(b) It did not account for the attraction between proton and neutrons

(c) It did not account for the stability of the atom

(d) There is actually no space between the nucleus and the electrons

 

Correct Answer:        (d) correct

Q(22). Angstrom is the unit of

(a) time                       (b) length

(c) Mass                      (d) Frequency

 

Correct Answer:        (d) correct

Q(23). Properties of waves are

(a) Wave length          (b) Wave number

(c) Frequency              (d) all

 

Correct Answer:        (d) correct

Q(24). The value of Plank’s constant is

(a) 6.62 x 10-34 J.s        (b) 6.62 x 10-27 J.s

(c) 6.62 x 10-21 J.s        (d) 6.62 x 10-31 J.s

 

Correct Answer:        (d) correct

Q(25). The wave number of the light emitted by a certain source is 2 x 106 m. The wavelength of the light will be

(a) 500nm                   (b) 500m

(c) 200nm                   (d) 5 x 107m

 

Correct Answer:        (d) correct

Q(26). The velocity of photon is

(a) Independent of its wavelength

(b) Depends on its wavelength

(c) Equal to square of its amplitude

(d) Depends on its amplitude

 

Correct Answer:        (d) correct

Q(27). Number of wave per unit length is called

(a)                              (b)

(c)                              (d) E

 

Correct Answer:        (d) correct

Q(28). The electron present in a particular orbit __________ energy

(a) Releases                 (b) Does not radiate

(c) Absorbs                 (d) None of these

 

Correct Answer:        (d) correct

Q(29). Splitting of spectral lines in closely spaced lines in presence of magnetic field is called

(a) Stark Effect              (b) Zeeman Effect

(c) Photoelectric Effect (d) Compton Effect

 

Correct Answer:        (d) correct

Q(30). Energy required to remove an electron from the outermost shell of its isolated gaseous atom in the ground state is

(a) Electron affinity    (b) Lattice Energy

(c) Ionization energy  (d) Crystal Energy

 

Correct Answer:        (d) correct

Q(31). The radius of first orbit of hydrogen atom is

(a)                   (b)

(c)                   (d)

 

Correct Answer:        (d) correct

Q(32). Radius of 3rd orbit of H-atom is

(a)                      (b)

(c)                      (d)

 

Correct Answer:        (d) correct

Q(33). Lines of Paschen series are produced when electrons jump from higher orbits to __________ Orbits.

(a) 1st                            (b) 2nd

(c) 3rd                           (d) 4th

 

Correct Answer:        (d) correct

Q(34). Value of the Redberg’s constant is

(a) 1.7904 x 107m-1      (b) 1.9768 x 102m-1

(c) 1.09678 x 107m-1       (d) 1.6 x 107m-1

 

Correct Answer:        (d) correct

Q(35). Bohr’s model of atom is contradicted by

(a) Planck quantum theory

(b) Pauli’s exclusion principle

(c) Heisenberg’s uncertainty principle

(d) All of the above

 

Correct Answer:        (d) correct

Q(36). Splitting of spectral lines when atoms are subjected to strong electric field is called

(a) Zeeman effect                   (b) Stark effect

(c) Photoelectric effect          (d) Compton effect

 

Correct Answer:        (d) correct

Q(37). In the ground state of an atom, the electron is present

(a) In the nucleus

(b) In the second shell

(c) Nearest to the nucleus

(d) Farthest from the nucleus

 

Correct Answer:        (d) correct

Q(38). The extent of bending of a light ray after passing through prism depends upon

(a) Wavelength of photons

(b) Wave number of photons

(c) Energy of photons

(d) Frequency of photons

 

Correct Answer:        (d) correct

Q(39). The velocity of photon is

(a) Equal to square of its amplitude

(b) Independent of its wavelength

(c) Equal to its wave number

(d) Equal to velocity of light

 

Correct Answer:        (d) correct

Q(40). Balmer series in hydrogen spectrum lies in the region

(a) Ultraviolet             (b) visible

(c) infrared                  (d) microwave

 

Correct Answer:        (d) correct

Q(41). Lyman series lies in

(a) UV region  (b) visible region

(c) IR region    (d) Microwave region

 

Correct Answer:        (d) correct

Q(42). The limiting line of Balmer Series lies in the region

(a) visible                    (b) U.V

(c) Near I.R.                 (d) Far I.R.

 

Correct Answer:        (d) correct

Q(43). Which rays are electromagnetic radiations and travel with the velocity of light

(a) Canal rays              (b) Alpha rays

(c) Beta rays                (d) Gamma rays

 

Correct Answer:        (d) correct

Q(44). X-rays were discovered by

(a) Moseley                 (b) Roentgen

(c) Rutherford             (d) de-Broglie

 

Correct Answer:        (d) correct

Q(45). Which of the following is the Moseley’s equation?

(a)

(b)

(c)                   

(d)

 

Correct Answer:        (d) correct

Q(46). Which one element will produce X-rays of high energy?

(a) Al                            (b) Cu

(c) Zn                           (d) U

 

Correct Answer:        (d) correct

Q(47). The position of a fast moving electron cannot be determined precisely. It is because the photon used to determine position have

(a) Longer wavelength

(b) Higher momentum

(c) Lesser energy

(d) Lesser momentum

 

Correct Answer:        (d) correct

Q(48). De-Broglie’s equation is characterized by

(a)            (b)

(c)            (d)

 

Correct Answer:        (d) correct

Q(49). Which particle has greater wavelength?

(a) electron                 (b) proton

(c) neutron                 (d)

 

Correct Answer:        (d) correct

Q(50). Which quantum number helps is study the orientation of an orbital in space?

(a) Principal quantum Number

(b) Spin quantum Number

(c) Magnetic quantum Number

(d) Azimuthal quantum Number

 

Correct Answer:        (d) correct

Q(51). With increase in the value of Principal Quantum Number ‘n’, the shape of the s-orbitals remains the same although their sizes

(a) Decrease

(b) Increase

(c) Remain the same

(d) May or may not remain the same

 

Correct Answer:        (d) correct

Q(52). Quantum number values for 3p orbitals are

(a)            (b)

(c)            (d)

 

Correct Answer:        (d) correct

Q(53). An orbital which is spherical and symmetrical is

(a) s-orbital                (b) p-orbital

(c) d-orbital                (d) f-orbital

 

Correct Answer:        (d) correct

Q(54). Quantum number values for 2p orbitals are?

(a)            (b)

(c)            (d)

 

Correct Answer:        (d) correct

Q(55). Orbitals having same energy are called

(a) hybrid orbitals         (b) valence orbitals

(c) degenerate orbitals  (d) d-orbitals

 

Correct Answer:        (d) correct

Q(56). When 6d orbital is complete, the entering electron goes into

(a) 7f                            (b) 7s

(c) 7p                           (d) 7d

 

Correct Answer:        (d) correct

Q(57). Which pair of transition elements shows abnormal electronic configuration?

(a) Sc and Zn               (b) Cu and Sc

(c) Zn and Cu               (d) Cu and Cr

 

Correct Answer:        (d) correct

Q(58). Correct order of energy in the given subshells is

(a)    5s > 3d > 3p > 4s

(b)    5s > 3d > 4s > 3p

(c)     3p > 3d > 5s > 4s

(d)    3p > 3d > 4s > 5s

 

Correct Answer:        (d) correct

Q(59). Number of electrons in the outermost shell of chloride ion (Cl) is

(a) 17                            (b) 3

(c) 1                              (d) 8

 

Correct Answer:        (d) correct

Q(60). The relative energies of 4s, 4p and 3d orbitals are in the order

(a) 3d < 4p < 4s           (b) 4s < 3d < 4p

(c) 4p < 4s < 3d           (d) 4p < 3d < 4s

 

Correct Answer:        (d) correct

Q(61). Electronic configuration of Manganese (Mn) is

(a) [Ar] 4s2 3d5             (b) [Ar] 4s2 3d4

(c) [Ar] 4s1 3d            (d) [Ar] 4s2 3d7

 

Correct Answer:        (d) correct

Q(62). Which one of the following pairs has the same electronic configuration as possessed by Neon (Ne-10)

(a) Na+, Cl–                           (b) K+, Cl

(c) Na+, Mg+                 (d) Na+, F

 

Correct Answer:        (d) correct

Q(63). There are four orbitals s, p, d and f. Which order is correct with respect to the increasing energy of the orbitals?

(a) 4s < 4p < 4d < 4f

(b) 4p < 4s < 4f < 4d

(c) 4s < 4f < 4p < 4d

(d) 4f < 4s < 4d < 4p

 

Correct Answer:        (d) correct

Q(64). Electronic configuration of Gold [Au79] is

(a) [Xe] 4f14, 5d10, 6s1   (b) [Xe] 4f10, 5d10, 6s2

(c) [Xe] 4f14, 5d9, 6s2    (d) [Xe] 4f14, 5d10, 6s2

 

Correct Answer:        (d) correct

Q(65). Number of neutron in 30Zn66

(a) 30                           (b) 35

(c) 38                           (d) 36

 

Correct Answer:        (d) correct

Q(66). The anomalous electronic configuration shown by chromium and copper among 3d series of elements is due to

(a) Colour of ions of these metals

(b) Variable oxidation state of metals

(c) Stability associated with this configuration

(d) Complex formation tendency of metals

 

Correct Answer:        (d) correct

Q(67). Maximum number of electrons in an orbital is

(a) 6                             (b) 10

(c) 14                            (d) 2

 

Correct Answer:        (d) correct

Q(68). The electronic configuration of an atom is 1s2 2s2 2p4. The number of unpaired electrons in this atom is

(a) 0                             (b) 2

(c) 4                             (d) 6

 

Correct Answer:        (d) correct

Q(69). After filling of 4f, the entering electron goes into

(a) 5d                           (b) 6p

(c) 6s                           (d) 4d

 

Correct Answer:        (d) correct

Q(70). The number of neutron present in?

(a) 39                           (b) 18

(c) 20                           (d) 19

 

Correct Answer:        (d) correct

Q(71). When 4s orbital is complete, the electron goes into

(a) 4p orbital               (b) 3d

(c) 4d                           (d) 4f

 

Correct Answer:        (d) correct

Q(72). The element which has maximum number of unpaired electrons is

(a) Cr24                         (b) Ca20

(c) Fe26                         (d) Cu29

 

Correct Answer:        (d) correct

Q(73). In which orbital electrons go after 6d?

(a) 7s                            (b) 7p

(c) 3s                            (d) 6f

 

Correct Answer:        (d) correct

Q(74). Which of the electronic configuration of nitrogen is correct?

(a) 1s2, 2s2, 2px1, 2py1, 2pz1

(b) 1s2, 2s2, 2px2, 2py1, 2pz1

(c) 1s2, 2s2, 2px2, 2py2, 2pz2

(d) 1s2, 2s2, 2px2, 2py2, 2pz1

 

Correct Answer:        (d) correct

Q(75). Which of the following electronic configurations represents an element that forms simple ion with a charge of -3?

(a) 1s2, 2s2, 2p6, 3s2, 3p1

(b) 1s2, 2s2, 2p6, 3s2, 3p3

(c) 1s2, 2s2, 2p6, 3s2, 3p6, 3d1, 4s2

(d) 1s2, 2s2, 2p6, 3s2, 3p6

 

Correct Answer:        (d) correct

Q(76). The correct electronic configuration of 24Cr is

(a) 1s2, 2s2, 2p6, 3s2, 3p6, 4s1, 3d5

(b) 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d4

(c) 1s2, 2s2, 2p6, 3s2, 3p6, 3d6

(d) 1s2, 2s2, 2p6, 3s2, 3p6, 4f6

 

Correct Answer:        (d) correct

Q(77). Which two elements are isotopes?

(a)         (b)

(c)         (d)

 

Correct Answer:        (d) correct

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