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Structure of Atom mcq for Class 11 Students

The charge signs of an electron, proton, and neutron are respectively

A) Positive, negative, and neutral

B) Neutral, positive, and negative

C) Negative, neutral, and positive

D) Negative, positive, and neutral

Option d – Negative, positive, and neutral

The number of electrons in the K shell of a hydrogen Molecule is

A) 1

B) 3

C) 4

D) 2

Option a – 1

Identify the correct statement

A) A neutron carries no electric charge.

B) Only protons are present in the center of an Atom.

C) Only neutrons occupy the center of an Atom.

D) Only electrons occupy the center of an Atom.

Option a – A neutron carries no electric charge.

The main particles that make up an atomic nucleus are called

A) Isotopes

B) Ions

C) Electrons

D) Nucleons

Option d – Nucleons

Calculate the Molecular Mass of C₂H₄O if C = 12.011, H = 1.008, and O = 15.999

A) 40.053

B) 34.053

C) 44.053

D) 16.053

Option c – 44.053

An Atom with atomic number 6 and 10 neutrons has an atomic Mass of

A) 4

B) 16

C) 10

D) 6

Option b – 16

The correct way to compute the formula unit Mass of a compound is

A) Multiply all atomic masses of the atoms in the formula.

B) Add all atomic weights of the atoms in the formula.

C) Add all atomic masses of the atoms in the formula.

D) Multiply all atomic weights of the atoms in the formula.

Option c – Add all atomic masses of the atoms in the formula.

Choose the accurate statement about an Atom

A) Atoms are not electrically neutral.

B) An Atom contains no positive charge.

C) Atoms overall are electrically neutral.

D) Atoms are partly electrically neutral.

Option c – Atoms overall are electrically neutral.

Approximate number of atoms used by Rutherford in his gold-foil alpha-scattering experiment was

A) 500

B) 900

C) 1000

D) 700

Option c – 1000

Number of water molecules in 9 g of water is nearly

A) 6.022 × 10²³

B) 9.023 × 10²³

C) 7.022 × 10²³

D) 3.011 × 10²³

Option d – 3.011 × 10²³

Identify the incorrect match of Molecule/formula unit and molar Mass

A) HCl – 36.5

B) CH₄ – 16

C) HNO – 62

D) NaCl – 58.5

Option c – HNO – 62

Correct statement about an Atom’s atomic number is

A) Number of neutrons equals the atomic number.

B) Sum of electrons and neutrons equals the atomic number.

C) Number of protons equals the atomic number.

D) Sum of protons and neutrons equals the atomic number.

Option c – Number of protons equals the atomic number.

Which of these are subatomic particles? 1. Electron 2. Proton 3. Neutron 4. Muon

A) 1, 2, 3 and 4

B) 1 and 4 only

C) 2 and 3 only

D) 1, 2 and 3 only

Option d – 1, 2 and 3 only

The two isotopes of chlorine are

A) ³⁶Cl and ³⁴Cl

B) ³⁶Cl and ³⁵Cl

C) ³⁷Cl and ³⁵Cl

D) ³⁵Cl and 37Cl

Option d – ³⁵Cl and 37Cl

The particle that determines an element’s chemical properties is

A) Protons

B) Electrons

C) Neutrons

D) Nucleus

Option b – Electrons

A cobalt isotope is used to treat

A) Goitre

B) Cancer

C) Beriberi

D) Crohn’s Disease

Option b – Cancer

Statement not supported by Rutherford’s alpha-scattering experiment is

A) Most of an atom’s space is empty.

B) Atomic radius is about 10⁵ times the nuclear radius.

C) Electrons travel in fixed circular orbits of definite energy.

D) Almost all atomic Mass is located in the nucleus.

Option c – Electrons travel in fixed circular orbits of definite energy.

Correctly matched pairs of phenomenon and discoverer are 1. James Chadwick : Photoelectric effect 2. Albert Einstein : Neutron 3. Marie Curie : Radium

A) 1, 2 and 3

B) 1 and 2 only

C) 2 and 3 only

D) 3 only

Option d – 3 only

The maximum electron capacity of the M shell is

A) 6

B) 8

C) 18

D) 32

Option c – 18

The Mass number of argon is 40. Which option is accurate?

A) Argon has 22 protons.

B) Argon contains 18 neutrons.

C) Argon has 18 electrons.

D) The total of protons and electrons in argon equals 40.

Option c – Argon has 18 electrons.

An element with atomic number 35 has how many valence electrons according to Bohr’s model?

A) 1

B) 3

C) 5

D) 7

Option d – 7

Rutherford’s alpha-particle scattering experiment revealed the existence of

A) Proton

B) Electron

C) Atomic nucleus

D) Neutron

Option c – Atomic nucleus

Boron occurs as two isotopes, ¹⁰B and ¹¹B, and its average atomic Mass is 10.81. What is the percentage of each isotope in a 100-atom sample?

A) 19% and 81%

B) 81% and 19%

C) 38% and 62%

D) 62% and 38%

Option a – 19% and 81%

The maximum number of electrons that can fill the first shell of an atom is

A) 2

B) 4

C) 8

D) 16

Option a – 2

For aluminium (atomic number 13, Mass number 27), which statement is incorrect?

A) Aluminium has 13 electrons.

B) Aluminium contains 13 protons.

C) Aluminium possesses 14 neutrons.

D) Aluminium shows a valency of 2.

Option d – Aluminium shows a valency of 2.

Which statement about the laws of chemical combination is false?

A) Equal volumes of all gases at identical temperature and pressure contain equal numbers of molecules.

B) When two elements form more than one compound, the masses of one element combining with a fixed Mass of the other are not in a definite ratio.

C) Matter can neither be created nor destroyed.

D) A compound always contains the same elements in fixed proportions by Mass.

Option b – When two elements form more than one compound, the masses of one element combining with a fixed mass of the other are not in a definite ratio.

The number of electrons in the given species, respectively, is

A) 1, 2, 2, 15

B) 1, 2, 1, 14

C) 2, 2, 2, 16

D) 0, 2, 1, 14

Option a – 1, 2, 2, 15

Which phenomenon was not explained by Rutherford’s atomic model?

A) Stability of the atom.

B) Existence of a nucleus at the center of the atom.

C) Comparison of atomic size with nuclear size.

D) Positive charge of the nucleus.

Option a – Stability of the atom.

Isobars of different elements share the same

A) Atomic number

B) Number of electrons

C) Mass number

D) Number of neutrons

Option c – Mass number

Which idea is not addressed by Dalton’s atomic theory?

A) Law of conservation of mass

B) Law of definite composition

C) Presence of subatomic particles in an atom

D) Law of multiple proportions

Option c – Presence of subatomic particles in an atom

Which observation is not a part of Rutherford’s nuclear model?

A) A neutral center in an atom called the nucleus.

B) Almost all atomic mass concentrated in the nucleus.

C) Electrons move around the nucleus in circular paths.

D) The nucleus is tiny compared with the atom’s overall size.

Option a – A neutral center in an atom called the nucleus.

The particle inside the atomic nucleus discovered by J. Chadwick is

A) Electron

B) Proton

C) Positron

D) Neutron

Option d – Neutron

Identify the correct statement.

A) A neutron forms by the combination of an electron and a proton, making it neutral.

B) The mass of an electron is about 1/2000 that of a proton.

C) An isotope of cobalt is used to treat goitre.

D) J. J. Thomson stated that the nucleus of an atom contains only neutrons.

Option b – The mass of an electron is about 1/2000 that of a proton.

John Dalton introduced his atomic theory, which stated that all atoms of a specific element are identical, in which year?

A) 1811

B) 1800

C) 1808

D) 1825

Option c – 1808

J. J. Thomson proposed which atomic model in 1898?

A) Gold-foil model

B) Plum-pudding model

C) Oil-drop model

D) Double-slit model

Option b – Plum-pudding model

Carl Anderson discovered the positively charged particle called the positron, having a mass equal to an electron, in which year?

A) 1912

B) 1932

C) 1942

D) 1922

Option b – 1932

Niels Bohr introduced his quantum theory–based hydrogen atom model, where certain physical quantities have discrete values, in which year?

A) 1919

B) 1921

C) 1913

D) 1909

Option c – 1913

Which combination of quantum numbers correctly describes an electron in the 4f orbital?

A) n = 3, l = 2, m = –2, s = +1/2

B) n = 4, l = 3, m = +1, s = +1/2

C) n = 4, l = 3, m = +4, s = +1/2

D) n = 4, l = 4, m = –4, s = –1/2

Option b – n = 4, l = 3, m = +1, s = +1/2

When an object is positively charged, it indicates

A) More electrons than protons

B) More protons than electrons

C) More neutrons than electrons

D) More neutrons than protons

Option b – More protons than electrons

What is the relative charge carried by a proton and a neutron?

A) –1 and +1 respectively

B) +1 and –1 respectively

C) +1 and 0 respectively

D) –1 and 0 respectively

Option c – +1 and 0 respectively

Which pair of “number–composition” statements is accurate?

A) Atomic number – Number of protons

B) Mass number – Sum of neutrons and protons

C) Both I and II

D) Neither I nor II

Option c – Both I and II

Which equation gives the correct calculation for the number of atoms?

A) (Given mass ÷ Molar mass) × Avogadro number

B) (Avogadro number ÷ Given mass) × Molar mass

C) (Molar mass ÷ Given mass) × Avogadro number

D) (Given mass ÷ Avogadro number) × Molar mass

Option a – (Given mass ÷ Molar mass) × Avogadro number

Identify the statement that does NOT fit Rutherford’s nuclear model of the atom.

A) The nucleus is extremely large compared to the atom.

B) Electrons orbit the nucleus in circular paths.

C) The atom contains a positively charged nucleus.

D) Almost all the atom’s mass is concentrated in the nucleus.

Option a – The nucleus is extremely large compared to the atom.

The count of atoms in exactly 12 g of Carbon-12 is called

A) Rydberg’s constant

B) Faraday’s constant

C) Avogadro’s constant

D) Planck’s constant

Option c – Avogadro’s constant

In the formula 2n² used for electronic configuration, “n” indicates

A) Total electrons

B) Total protons

C) The principal shell number

D) Number of valence electrons

Option c – The principal shell number

According to Dalton’s theory, atoms combine in small whole-number ratios to create

A) Neutrons

B) Molecules

C) Protons

D) Compounds

Option d – Compounds

If a nucleus were the size of a cricket ball, the approximate radius of the atom would be about

A) 5 km

B) 0.5 km

C) 0.05 km

D) 0.005 km

Option a – 5 km

The first electron shell, closest to the nucleus, can hold a maximum of

A) 2 electrons

B) 8 electrons

C) 4 electrons

D) 6 electrons

Option a – 2 electrons

One mole of aluminium sulphate, Al₂(SO₄)₃, contains how many moles of oxygen atoms?