MCQ on Inside the Atom Class 8

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MCQ on Inside the Atom Class 8. We covered all the atomic structure class 8 icse mcq in this post for free so that you can practice well for the exam.

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MCQ on What is Inside the Atom for Students

The proton is heavier than an electron by ………

1) 1850 times

2) 1840 times

3) 1000 times

4) 100 times

Option 2 – 1840 times

Carbon-12 atom has ……….

1) 6 electrons, 6 protons, 6 neutrons

2) 6 electrons, 12 protons, 6 neutrons

3) 12 electrons, 6 protons, 6 neutrons

4) 18 electrons, 6 protons and 6 neutrons

Option 1 – 6 electrons, 6 protons, 6 neutrons

Chadwick got the Nobel prize for the discovery of

1) protons

2) electrons

3) neutrons

4) nucleons

Option 3 – neutrons

Mass number is equal to the

1) protons + neutrons

2) protons + electrons

3) electrons + neutrons

4) neutrons – protons

Option 1 – protons + neutrons

The elements X has a 2 valence electrons it is a

1) metal

2) non metal

3) metalloid

4) alloy

Option 1 – metal

In Rutherford’s alpha-scattering experiment, a foil was used

1) platinum

2) silver

3) magnesium

4) gold

Option 4 – gold

An element has an electronic configuration 2,8,7 Its valency is

1) 1

2) 7

3) 3

4) 0

Option 1 – 1

The fixed circular paths around the nucleus are called

1) orbits

2) shells

3) orbitals

4) Both 1 & 2

Option 4 – Both 1 & 2

Nucleus was discovered by

1) Rutherford

2) Thomson

3) Chadwick

4) Bohr

Option 1 – Rutherford

Electrons was discovered by

1) Rutherford

2) Thomson

3) Chadwick

4) Bohr

Option 2 – Thomson

The K, L and M shells of an atom are completely filled. Its atomic number is

1) 30

2) 20

3) 10

4) 12

Option 1 – 30

Which of the air pressures is appropriate for the production of cathode rays in the discharge tube?

1) 1 cm Hg

2) 1 mm Hg

3) 0.001 cm Hg

4) 0.001 mm Hg

Option 4 – 0.001 mm Hg

Cathode rays are deflected towards ……….

1) positive electrode

2) negative electrode

3) both electrodes

4) none of the electrodes

Option 1 – positive electrode

Electron was discovered by ………

1) Chadwick

2) Thomson

3) Goldstein

4) Bohr

Option 2 – Thomson

An atom has a mass number of 23 and atomic number 11. The number of protons are ……….

1) 11

2) 12

3) 23

4) 44

Option 1 – 11

The mass of the atom is determined by ………

1) neutrons

2) neutron and proton

3) electron

4) electron and neutron

Option 2 – neutron and proton

Almost the entire mass of an atom is concentrated in the ……..

1) proton

2) electrons

3) nucleus

4) neutrons

Option 3 – nucleus

According to Rutherford’s atomic model, the electrons inside the atom are ………..

(A) centralized

(B) deviated

(C) not stationary

(D) stationary

Option c – not stationary

In a hydrogen atom, if the difference in the energy of the electron in n = 3 and n = 4 orbits is E, then the ionization energy of the hydrogen atom is

(A) 13.21E

(B) 7.28E

(C) 20.57E

(D) 3.33E

Option c – 20.57E

The ratio of minimum to maximum wavelength in the Balmer series is

(A) 5 : 9

(B) 5 : 36

(C) 1 : 4

(D) 3 : 4

Option a – 5 : 9

Which of the following statements about the Bohr model of the hydrogen atom is TRUE?

(A) The acceleration of the electron in the n = 2 orbit is more than that in the n = 1 orbit.

(B) The angular momentum of an electron in the n = 2 orbit is more than that in the n = 1 orbit.

(C) The kinetic energy of an electron in the n = 2 orbit is more than that in the n = 1 orbit.

(D) The potential energy of an electron in the n = 2 orbit is less than that in the n = 1 orbit.

Option b – The angular momentum of an electron in the n = 2 orbit is more than that in the n = 1 orbit.

As an electron makes a transition from a higher orbit to the lower orbit of a hydrogen-like atom/ion

(A) kinetic energy, potential energy, and total energy decrease.

(B) its kinetic energy increases but potential energy and total energy decrease.

(C) kinetic energy and total energy decrease but potential energy increases.

(D) kinetic energy decreases, potential energy increases but the total energy remains the same.

Option b – its kinetic energy increases but potential energy and total energy decrease.

Which of the following is correct for the number of spectral lines observed in going from the Lyman series to the Pfund series when an electron jumps from the 10th orbit?

(A) Increases.

(B) Decreases.

(C) Unchanged.

(D) May decrease or increase.

Option b – Decreases.

The concept of stationary orbits was proposed by ………

(A) Niels Bohr

(B) Rutherford

(C) J.J. Thomson

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(D) Balmer

Option a – Niels Bohr

If an electron jumps from the 3rd orbit to the 1st orbit, then it will

(A) absorb energy.

(B) release energy.

(C) possess the same energy.

(D) lose -13.6 eV energy.

Option b – release energy.

The ionization energy of hydrogen is 13.6 eV. The energy of the photon released when an electron jumps from the second excited state to the ground state of a hydrogen atom is

(A) 3.4 eV

(B) 1.51 eV

(C) 12.09 eV

(D) 10.2 eV

Option c – 12.09 eV

With the decrease in principal quantum number, the energy difference between the two successive energy levels

(A) increases.

(B) decreases.

(C) remains constant.

(D) sometimes increases and sometimes decreases.

Option a – increases.

The area of the electron orbit for the ground state of a hydrogen atom is A. What will be the area of the electron orbit corresponding to the third excited state?

(A) 27A

(B) 64A

(C) 81A

(D) 256A

Option d – 256A

Assertion: The density of the nuclei of all the atoms are same. Reason: The density of the nucleus depends on the mass number.

(A) The assertion is True, Reason is True; Reason is a correct explanation for Assertion.

(B) The assertion is True, and Reason is True; Reason is not a correct explanation for Assertion.

(C) The assertion is True, Reason is False.

(D) The assertion is False, Reason is False.

Option c – The assertion is True, Reason is False.

The minimum energy required to take out only an electron from the ground state of He is one

(A) 13.6 eV

(B) 54.4 eV

(C) 27.2 eV

(D) 6.8 eV

Option b – 54.4 eV

The required to knock electron energy from the third orbit in eV will be

(A) 1.51

(B) 0.38

(C) 13.6

(D) 3.4

Option a – 1.51

The force acting between proton and proton inside the nucleus is ………. force.

(A) Coulomb

(B) Nuclear

(C) Coulomb and nuclear

(D) Gravitational

Option c – Coulomb and nuclear

The ionization potential of a hydrogen atom is 13.6 eV. Hydrogen atoms in the ground state are excited by monochromatic radiation of photon energy 12.75 eV. The spectral lines emitted by hydrogen atoms according to Bohr’s theory will be

(A) Six

(B) Two

(C) Three

(D) Four

Option a – Six

In which of the following atoms and molecules, will the spectral line of minimum wavelength be produced for the transition from n = 2 to n = 1?

(A) Deuterium atom.

(B) Hydrogen atom.

(C) Di-ionized lithium.

(D) Uni-ionized helium.

Option c – Di-ionized lithium.

The ratio of the velocity of the electron in the first orbit to that in the third orbit is

(A) 27 : 1

(B) 9 : 1

(C) 3 : 1

(D) 1 : 3

Option c – 3 : 1

As per the Bohr model, the minimum energy (in eV) required to remove an electron from the ground state of a doubly ionized Li atom (Z = 3) is

(A) 1.51

(B) 13.6

(C) 40.8

(D) 122.4

Option d – 122.4

The ratio of maximum to minimum wavelength in the Balmer series is

(A) 5 : 9

(B) 36 : 9

(C) 9 : 5

(D) 3 : 4

Option c – 9 : 5

Which of the following transitions has a higher frequency?

(A) 4→3

(B) 3 →1

(C) 4→2

(D) 3→2

Option b – 3 → 1

What would be the possible number of elements, if elements with principal quantum number n > 4 did not exist in nature?

(A) 60

(B) 32

(C) 28

(D) 110

Option a – 60

The size of the nucleus in an atom is almost equal to

(A) 1 weber

(B) 1 tesla

(C) 1 fermi

(D) 1 henry

Option c – 1 fermi

The minimum excitation potential of Bohr’s fin orbit in a hydrogen atom is ( Class 9 Atoms and Molecules MCQ )

(A) 13.6 V

(B) 3.4 V

(C) 10.2 V

(D) 10.2 eV

Option c – 10.2 V

A monochromatic beam of light is absorbed by a collector of ground-state hydrogen atom in such a way that six different wavelengths are observed when hydrogen relaxes back to the ground state The wavelength of the incident beam is

(A) 97 nm

(B) 91 nm

(C) 68 nm

(D) 85 nm

Option a – 97 nm

In the Bohr model of the hydrogen atom, the highest orbit corresponds to

(A) infinite energy.

(B) the maximum energy.

(C) the minimum energy.

(D) zero energy.

Option b – the maximum energy.

The percentage of mass converted into energy in nuclear fission is about

(A) 10%

(B) 0.01%

(C) 0.1%

(D) 1%

Option c – 0.1%

In alpha decay, the ratio of neutron to proton

(A) increases.

(B) decreases.

(C) remains constant.

(D) may increase or decrease.

Option a – increases.

A sample of the radioactive element has a mass of 20 g at an instant t = 0. What is the approximate mass of this element in the sample after two mean lives?

(A) 5 g

(B) 1.35 g

(C) 2.71 g

(D) 0.8 g

Option c – 2.71 g

The binding energy of the nucleus is the energy ( mcq on inside the atom class 8 )

(A) equivalent to that of the mass of the nucleus.

(B) equivalent to that of an atom as a whole.

(C) equivalent to that of packing fraction.

(D) equivalent to that of the mass defect.

Option d – equivalent to that of the mass defect.

A radioactive element X with a half-life period of 2 hours decays giving a stable element Y. If the ratio of X and Y atoms is 1 : 7, then the value of t is

(A) 4 hours

(B) 14 hours

(C) 6 hours

(D) Between 4 and 6 hours

Option c – 6 hours

The half-life of a radioactive substance is 30 minutes. The time taken between 50% decay and 87.5% decay of the substance will be

(A) 15 minutes

(B) 30 minutes

(C) 10 minutes

(D) 60 minutes

Option d – 60 minutes

The number of nuclei undergoing the decay per unit of time is

(A) inversely proportional to the number of unchanged nuclei present at that instant.

(B) directly proportional to the number of unchanged nuclei present at that instant.

(C) equal to the number of unchanged nuclei present at that instant.

(D) zero.

Option b – directly proportional to the number of unchanged nuclei present at that instant.

A certain mass of hydrogen is changed to helium by the process of fusion. The mass defect in the fusion reaction is 0.03866 u. The liberated per u is (given 1 u = 931 MeV) energy

(A) 3.59 MeV

(B) 35 MeV

(C) 9 MeV

(D) 13.35 MeV

Option c – 9 MeV

During negative beta decay,

(A) a neutron in the nucleus decays emitting an electron.

(B) a proton that is already present within the nucleus is ejected.

(C) a part of the binding energy of the nucleus is converted into an electron.

(D) an atomic electron is ejected.

Option a – a neutron in the nucleus decays emitting an electron.

If a radioactive substance has a mean life of 5 hours, then in this time ( mcq on inside the atom class 8 )

(A) all active nuclei will decay

(B) less than 50% of the active nuclei will decay

(C) less than 60% of the active nuclei will decay

(D) more than 70% of the active nuclei will decay

Option d – more than 70% of the active nuclei will decay

If a radioactive nucleus emits a beta particle, then the parent and daughter nuclei are ………

(A) isotopes

(B) isotones

(C) isomers

(D) isobars

Option d – isobars

16 g of radioactive radon is kept in a container. How much radon will disintegrate in 18 days? The half-life of radon is 3.6 days. ( mcq on inside the atom class 8 )

(A) 0.5 g

(B) 3.6 g

(C) 16 g

(D) 2 g

Option a – 0.5 g

The masses of the proton and neutron are 1.0073 a.m.u. and 1.0087 a.m.u. respectively. The neutrons and protons combine to form a helium nucleus (alpha particles) of mass 4.0015 a.m.u. What is the binding energy of the helium nucleus thus formed? (1 a.m.u. 931 MeV)

(A) 14.2 MeV

(B) 28.4 MeV

(C) 20.8 MeV

(D) 27.3 MeV

Option b – 28.4 MeV

The half-life of a radioactive substance is 26 minutes. The time (in minutes) taken between 40% decay and 85% decay of the same radioactive substance is

(A) 13

(B) 52

(C) 26

(D) 676

Option b – 52

Choose the INCORRECT one :

(A) The energy equivalent to that of mass defect is called the binding energy of the nucleus.

(B) Mass defect per nucleon is called packing fraction.

(C) The energy equivalent to 1 amu is 931 MeV.

(D) The energy and mass are not interconvertible.

Option d – The energy and mass are not interconvertible.

After 24 hours, the activity of a radioactive sample is 3000 DPS (disintegrations per second). After another 12 hours, the activity reduces to 1500 DPS. The initial activity of the sample in DPS is

(A) 1000

(B) 9000

(C) 3000

(D) 12000

Option d – 12000

In any fission process, the ratio of the mass of the parent nucleus to the mass of fission products is ……….

(A) greater than I

(B) less than I

(C) depends on the mass of the parent nucleus

(D) equal to I

Option a – greater than I

A radioactive sample with a half-life of 1 month has the label: Activity = 2 microcurie on 1-3-2013. What was its activity before 3 months?

(A) 16 microcurie

(B) 4 microcurie

(C) 1 microcurie

(D) 8 microcurie

Option a – 16 microcurie

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8 thoughts on “MCQ on Inside the Atom Class 8”

  1. It’s very useful you can add few questions covering dalton’s atomic theory Rutherford gold foil experiment also

    Reply

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