Atoms of different elements having same mass number

Atoms of same elements having same mass number

Atoms of different elements having same number of neutrons

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NEET • CHEMISTRY • STRUCTURE OF ATOM

Structure of atom practice · Mixed difficulty

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31 Medium

31 of 492

Understanding +4 | -1

Threshold wavelength depends upon :

View answer and explanation

Correct option: C

Work function

Option C (Work function) is correct because the threshold wavelength is inversely proportional to the work function of the metal.

32 Medium

32 of 492

Analyzing +4 | -1

When

z

is doubled in an atom, which of the following statements are consistent with Bohr’s theory?

View answer and explanation

Correct option: C

Velocity of electron in an orbit is doubled

Option C (Velocity of electron in an orbit is doubled) is correct because, according to Bohr's theory, the velocity of an electron is directly proportional to the atomic number Z.

33 Medium

33 of 492

Application +4 | -1

The radius of second Bohr’s orbit of hydrogen atom is

View answer and explanation

Correct option: C

0.2116 nm

Option C (0.2116 nm) is correct because the radius of the nth Bohr orbit is given by

r_n = n^2 * a_0

, where

a_0

is the Bohr radius (0.0529 nm). For the second orbit (n=2),

r_2 = 2^2 * 0.0529 nm = 0.2116 nm

34 Easy

34 of 492

Application +4 | -1

If threshold wavelength

\left( {{\lambda ^0}} \right)

for ejection of electron from metal is 330 nm. Then work function for the photo electric emission is

View answer and explanation

Correct option: C

6 \times {10^{ - 19}}J

Option C is correct. The work function is calculated using the formula φ = hc/λ, resulting in approximately 6 × 10^-19 J.

35 Medium

35 of 492

Application +4 | -1

The average molar mass of chlorine is

35.5\,g\,\,\,mo{l^{ - 1}}.

The ratio of

{}^{35}Cl

{}^{37}Cl

in naturally occurring chlorine is close to

View answer and explanation

Correct option: B

0.125694444

Option A (0.167361111) is incorrect. The correct answer is derived from setting up a weighted average equation and solving for the ratio of the isotopes.

36 Easy

36 of 492

Analyzing +4 | -1

{E_e}\,,\,{E_\alpha }\,\& {E_P}

{E_\alpha }

and

{E_P}

represents the kinetic energies of electron, -particle and a proton de Broglie wavelength then

View answer and explanation

Correct option: D

{E_e}\,\, > {E_P}\,\, > = {E_\alpha }

Option D (

{E_e}\,\, > {E_P}\,\, > = {E_\alpha }

) is correct because the kinetic energy is inversely proportional to the mass when de Broglie wavelength is constant.

37 Medium

37 of 492

Understanding +4 | -1

Angular momentum of electron in 3rd stationary orbit of hydrogen atom is

View answer and explanation

Correct option: B

\frac{{3h}}{{2\pi }}

Option B (

\frac{{3h}}{{2\pi }}

) is correct because the angular momentum of an electron in the nth orbit is given by

L = n \frac{h}{{2\pi}}

, and for the 3rd orbit, n=3.

38 Medium

38 of 492

Remembering +4 | -1

Select the incorrect option among the following

View answer and explanation

Correct option: A

\mathrm{e} / \mathrm{m}

ratio of proton is

1.758820 \times 10^{11} \mathrm{C} \mathrm{g}^{-1}

The correct answer is A (

\mathrm{e} / \mathrm{m}

ratio of proton is

1.758820 \times 10^{11} \mathrm{C} \mathrm{g}^{-1}

) because the e/m ratio of a proton is significantly smaller than that of an electron.

39 Easy

39 of 492

Application +4 | -1

The uncertainty in the velocity of a particle of mass

6.626\,\,x\,\,{10^{^{ - 28}}}Kg\,\,is\,\,1\,\,x\,\,{10^{^{ - 6}}}

m/s. What is the uncertainty in its position ( in nm )

View answer and explanation

Correct option: D

1/4\pi

Option D (

1/4\pi

) is correct because Heisenberg's uncertainty principle states that

\Delta x \Delta p \geq \frac{h}{{4\pi}}

, where

\Delta p = m \Delta v

. Solving for

\Delta x

gives

\Delta x = \frac{h}{{4\pi m \Delta v}} = \frac{{6.626 \times 10^{-34}}}{{4\pi \times 6.626 \times 10^{-28} \times 1 \times 10^{-6}}} = \frac{1}{{4\pi}} \times 10^{-9} m = \frac{1}{{4\pi}} nm

40 Medium

40 of 492

Analyzing +4 | -1

The 'm' value for an electron in an atom is equal to the number of m value for

l = 1

. The electron may be present in

View answer and explanation

Correct option: B

5{f_{x\left( {{x^2} - {y^2}} \right)}}

Option B (

5{f_{x\left( {{x^2} - {y^2}} \right)}}

) is correct because for l=1, there are 3 m values (-1, 0, +1), and the f orbital (l=3) can have m values of -3, -2, -1, 0, 1, 2, 3. The question states that the 'm' value for an electron is equal to the number of m values for l=1 (which is 3). Therefore, we need an orbital that can have m = 3, which is only possible for f orbitals.

41 Medium

41 of 492

Analyzing +4 | -1

Which set of quantum number are not possible

View answer and explanation

Correct option: B

\begin{array}{cccccccccccccccccccc} n&l&m&s\\ 2&2&1&{ + 1/2} \end{array}

Option B is not possible because if n=2, l can only be 0 or 1. l cannot be equal to n.

42 Hard

42 of 492

Remembering +4 | -1

Davisson and Germer's experiment showed that

View answer and explanation

Correct option: C

Electrons show wave nature

Option A (

n,\alpha ,p,e

) is correct because the e/m ratio is smallest for the neutron (0), followed by the alpha particle (charge +2, mass 4), then the proton (charge +1, mass 1), and largest for the electron (charge -1, very small mass).

43 Hard

43 of 492

Analyzing +4 | -1

Statement-1 : Nuclide

{ }^{30} {Al}_{13}

is less stable than

{ }^{40} {Ca}_{20}

Statement-2 : Nuclide having odd number of protons and neutrons are generally unstable.

View answer and explanation

Correct option: A

Statement- 1 is True, Statement- 2 is True, Statement- 2 is a correct explanation for Statement - 3

Option A (Statement- 1 is True, Statement- 2 is True, Statement- 2 is a correct explanation for Statement - 3) is correct because

{ }^{30} {Al}_{13}

has an odd number of protons and neutrons, making it less stable than

{ }^{40} {Ca}_{20}

, which has an even number of both.

44 Medium

44 of 492

Remembering +4 | -1

Which of the following electromagnetic radiation have greater frequency?

View answer and explanation

Correct option: A

\gamma

-rays

Option A (

\gamma

-rays) is correct because gamma rays have the highest frequency in the electromagnetic spectrum.

45 Medium

45 of 492

Understanding +4 | -1

Magnitude of kinetic energy in an orbit is equal to

View answer and explanation

Correct option: A

Half of the potential energy

Option A (Half of the potential energy) is correct because the magnitude of kinetic energy is half the magnitude of potential energy in an orbit, with opposite signs.

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46 Easy

46 of 492

Analyzing +4 | -1

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: Loss of electron from hydrogen atom results in nucleus of

\sim 1.5 \times 10^{-3} \, \mathrm{pm}

size.

Reason R: Proton

\left(\mathrm{H}^{+}\right)

always exists in combined form.

In the light of the above statements, choose the most appropriate answer from the options given below:

View answer and explanation

Correct option: D

Both A and R are correct but R is NOT the
correct explanation of A

Option D (Both A and R are correct but R is NOT the correct explanation of A) is correct because both the assertion and the reason are true statements, but the reason does not explain the assertion.

47 Medium

47 of 492

Remembering +4 | -1

Azimuthal quantum number defines

View answer and explanation

Correct option: B

Angular momentum of electron

Option B (Angular momentum of electron) is correct because the azimuthal quantum number (l) is directly related to the angular momentum of an electron.

48 Easy

48 of 492

Analyzing +4 | -1

Which among the following species have the same number of electrons in its outermost as well as penultimate shell?

View answer and explanation

Correct option: D

\mathrm{C}{\mathrm{a}^{2 + }}

Option D (

\mathrm{C}{\mathrm{a}^{2 + }}

) is correct because Calcium (Ca) loses two electrons to form Ca2+, resulting in the same number of electrons (8) in both the outermost (2p) and penultimate (3p) shells.

49 Easy

49 of 492

Application +4 | -1

Suppose

{10^{ - 17}}

J of light energy is needed by the interior of a human eye to see an object. Calculate the number of photons of green light (

({\lambda _\;} = 550

nm) needed to generate this minimum amount of energy

View answer and explanation

Correct option: C

Option C is correct. The number of photons is calculated by dividing the total energy needed by the energy of a single photon, resulting in approximately 28 photons.

50 Medium

50 of 492

Remembering +4 | -1

'{R_H}'

is the Rydberg constant, then the energy of an electron in the ground state of hydrogen atom is:

View answer and explanation

Correct option: D

- {R_H}hc

Option D (

-{R_H}hc

) is correct because the energy of an electron in the ground state of a hydrogen atom is given by

-R_Hhc

51 Easy

51 of 492

Remembering +4 | -1

Isotopes are

View answer and explanation

Correct option: C

Atoms of same elements having different mass number

Option C is correct because isotopes are atoms of the same element that have different mass numbers due to differing numbers of neutrons.

52 Medium

52 of 492

Remembering +4 | -1

The principal quantum number of an atom represents:

View answer and explanation

Correct option: A

Size and energy of the orbit

Option A is correct because the principal quantum number (n) primarily determines the size and energy of an electron's orbit.

53 Medium

53 of 492

Understanding +4 | -1

Increase in the frequency of the incident radiations increases the:

View answer and explanation

Correct option: C

Kinetic energy of photo-electrons

Option C (Kinetic energy of photo-electrons) is correct because, according to the photoelectric effect, the kinetic energy of emitted photoelectrons increases with the frequency of the incident radiation.

54 Medium

54 of 492

Remembering +4 | -1

Rutherford's scattering experiment is related to the size of the

View answer and explanation

Correct option: A

Nucleus

Option A (Nucleus) is correct because Rutherford's scattering experiment, involving alpha particles bombarding a gold foil, provided evidence for the existence and size of the atomic nucleus.

55 Medium

55 of 492

Application +4 | -1

If the following matter travel with equal velocity, the longest wavelength is that of

View answer and explanation

Correct option: A

electron

Option A (electron) is correct because, according to de Broglie's equation, wavelength is inversely proportional to mass. The electron has the smallest mass among the options.

56 Medium

56 of 492

Application +4 | -1

The ratio of radii of two nuclei with mass numbers 27 and 64 is

View answer and explanation

Correct option: B

\frac{3}{4}

Option B (3/4) is correct because the nuclear radius is proportional to the cube root of the mass number, so the ratio is (27/64)^(1/3) = 3/4.

57 Medium

57 of 492

Application +4 | -1

Which has the highest e/m ratio?

View answer and explanation

Correct option: B

{\mathrm{H}^ + }

Option B (

{\mathrm{H}^ + }

) is correct because it has the highest charge-to-mass ratio (e/m). It has a single proton and no neutrons or electrons, giving it a large charge relative to its small mass.

58 Easy

58 of 492

Understanding +4 | -1

As the number of orbit increase from the nucleus, the difference between the adjacent energy levels:

View answer and explanation

Correct option: C

Decreases

Option C (Decreases) is correct because as the number of orbits increases, the energy levels get closer together, thus the difference between adjacent energy levels decreases.

59 Easy

59 of 492

Remembering +4 | -1

Electromagnetic radiation with maximum wavelength is

View answer and explanation

Correct option: B

Radio wave

Option C (0) is correct because electrons are located outside the nucleus in the electron cloud.

60 Medium

60 of 492

Analyzing +4 | -1

STATEMENT-1 : Disintegration of

{ }_1 \mathrm{H}^3

(tritium) is accompanied by

\beta

-emission.

STATEMENT-2: Tritium has high

n / p

ratio.

View answer and explanation

Correct option: A

If both the statements are TRUE and STATEMENT-2 is the correct explanation of STATEMENT-1

Option A is correct because tritium has a high neutron-to-proton ratio, making it unstable and prone to beta decay, which involves the emission of a beta particle.

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