Journey Inside the Atom Class 9 MCQ Questions Science Chapter 8

These Class 9 Science MCQ and Class 9 Science Exploration Chapter 8 MCQ Online Test with Answers Journey Inside the Atom focus on both theory and practical applications.

Class 9 Science Chapter 8 Journey Inside the Atom MCQ

Journey Inside the Atom MCQ

Class 9 Science Chapter 8 MCQ Online Test
Question 1.
Who among the following first proposed that matter is made of extremely small indivisible particles called parmanu?
(a) Democritus
(b) Acharya Kanada
(c) John Dalton
(d) Rutherford
Answer:
(b) Acharya Kanada

Question 2.
Which statement best explains why Dalton’s atomic theory was accepted over earlier ideas?
(a) It was based on imagination
(b) It was based on experiments
(c) It included electrons
(d) It explained nuclear structure
Answer:
(b) It was based on experiments

Question 3.
The main limitation of Rutherford’s model was that it could not explain:
(a) Presence of nucleus
(b) Charge of electrons
(c) Stability of atom
(d) Mass of atom
Answer:
(c) Stability of atom

Question 4.
Which scientist introduced the idea of fixed energy levels?
(a) Rutherford
(b) Dalton
(c) Bohr
(d) Thomson
Answer:
(c) Bohr

Question 5.
The maximum number of electrons in the L-shell is:
(a) 2
(b) 8
(c) 18
(d) 32
Answer:
(b) 8

Question 6.
Which subatomic particle contributes least to the mass of an atom?
(a) Electron
(b) Neutron
(c) Proton
(d) All equal
Answer:
(a) Electron

Question 7.
An atom with atomic number 15 will have how many electrons?
(a) 10
(b) 15
(c) 20
(d) 30
Answer:
(b) 15

Question 8.
Which of the following determines the identity of an element?
(a) Mass number
(b) Number of neutrons
(c) Valency
(d) Atomic number
Answer:
(d) Atomic number

Question 9.
The charge on a neutron is:
(a) +1
(b) -1
(c) 0
(d) Depends on the atom
Answer:
(c) 0

Question 10.
Which of the following are true for an element? (NCERT Exemplar)
(i) Atomic number = Number of protons + Number of electrons
(ii) Mass number = Number of protons + Number of neutrons
(iii) Atomic mass = Number of protons + Number of neutrons
(iv) Atomic number = Number of protons + Number of electrons
Choose from the options given below.
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (ii) and (iv)
Answer:
(d) (ii) and (iv)

Question 11.
Which of the following model describes the structure of an atom proposed by Thomson’
Answer:

Question 12.
Atomic models have been improved over the years. Arrange the following atomic models in the order of their chronology.
(i) Rutherford’s atomic model
(ii) Thomson’s atomic model
(iii) Bohr’s atomic model
(a) (i), (ii) and (iii)
(b) (ii), (iii) and (i)
(c) (ii), (i) and (iii)
(d) (iii), (ii) and (i)
Answer:
(c) (ii), (i) and (iii)

Question 13.
Rutherford’s alpha (α) particle scattering experiment resulted in the discovery of
(a) electron
(b) proton
(c) nucleus in the atom
(d) atomic mass.
Answer:
(c) nucleus in the atom

Question 14.
The number of electrons in an element X is 15, and the number of neutrons is 16. Which of the following is the correct representation of the element?
(a) ³¹₁₅X
(b) ³¹₁₆X
(c) ¹⁶₁₅x
(d) ¹⁵₁₆X
Answer:
(a) ³¹₁₅X

Question 15.
Which of the following statements about Rutherford’s model of atom are correct?
(i) considered the nucleus as positively charged
(ii) established that the α-particles are four times as heavy as a hydrogen atom
(iii) can be compared to solar system
(iv) was in agreement with Thomson’s model
(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) only (i)
Answer:
(a) (i) and (iii)

Question 16.
Which of the following are true for an element?
(i) Atomic number = Number of protons + Number of electrons
(ii) Mass number = Number of protons + Number of neutrons
(iii) Atomic mass = Number of protons + Number of neutrons
(iv) Atomic number = Number of protons + Number of electrons
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (ii) and (iv)
Answer:
(d) (ii) and (iv)

Question 17.
The electron distribution in an aluminium atom is
(a) 2, 8, 3
(b) 2, 8, 2
(c) 8,2,3
(d) 2,3,8
Answer:
(a) 2, 8, 3

Question 18.
In the Thomson’s model of atom, which of the following statements are correct?
(i) The mass of the atom is assumed to be uniformly distributed over the atom
(ii) The positive charge is assumed to be uniformly distributed over the atom
(iii) The electrons are uniformly distributed in the positively charged sphere
(iv) The electrons attract each other to stabilise the atom
(a) (i), (ii) and (iii)
(b) (i) and (iii)
(c) (i) and (iv)
(d) (i), (iii) and (iv)
Answer:
(a) (i), (ii) and (iii)

Question 19.
Which one of the following is a correct electronic configuration of sodium?
(a) 2,8
(b) 8,2,1
(c) 2, 1,8
(d) 2,8, 1
Answer:
(d) 2,8, 1

Question 20.
Which of the following statement is always correct?
(a) An atom has equal number of electrons and protons.
(b) An atom has equal number of electrons and neutrons.
(c) An atom has equal number of protons and neutrons.
(d) An atom has equal number of electrons, protons and neutrons.
Answer:
(a) An atom has equal number of electrons and protons.

Journey Inside the Atom Class 9 Assertion and Reason Questions

Directions (Q. No. 1 to 14): Each question below consists of an Assertion (A) and a Reason (R).
Use the following key to choose the appropriate answer.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.

Question 1.
Assertion (A): Atoms are electrically neutral.
Reason (R): The number of protons in an atom is equal to the number of electrons.
Answer:
(a) Both A and R are true, and R is the correct explanation of A.

Question 2.
Assertion (A): Isotopes have similar chemical properties.
Reason (R): Isotopes have the same number of electrons.
Answer:
(a) Both A and R are true, and R is the correct explanation of A.

Question 3.
Assertion (A): The atomic number determines the identity of an element.
Reason (R): Atomic number is equal to the number of neutrons.
Answer:
(c) A is true but R is false.

Question 4.
Assertion (A): Protium, deuterium and tritium are isotopes of hydrogen.
Reason (R): They have different atomic numbers but same mass number therefore, they are called isotopes.
Answer:
(c) A is true but R is false.

Question 5.
Assertion (A): Thomson’s model explained the presence of a nucleus.
Reason (R): Positive charge was uniformly distributed in the atom.
Answer:
(d) A is false but R is true.

Question 6.
Assertion (A): Isotopes of an element have the same chemical properties.
Reason (R): Isotopes have the same number of protons and electrons.
Answer:
(a) Both A and R are true, and R is the correct explanation of A.

Question 7.
Assertion (A): Mass number of an element is always an integer.
Reason (R): Mass number is the sum of the
number of protons and neutrons is an atom, both of which are whole numbers.
Answer:
(a) Both A and R are true, and R is the correct explanation of A.

Question 8.
Assertion (A): Mass number of an element is always an integer.
Reason (R): Mass number is the sum of the number of protons and neutrons is an atom, both of which are whole numbers.
Answer:
(a) Both A and R are true, and R is the correct explanation of A.

Question 9.
Assertion (A): The mass of the total number of protons and neutrons is a measure of the approximate mass of an atom.
Reason (R): The mass of an electron is negligible.
Answer:
(a) Both A and R are true, and R is the correct explanation of A.

Question 10.
Assertion (A): Electrons moving in the same orbit does not loss energy.
Reason (R): On jumping from higher to lower energy level, the electron will emit energy
Answer:
(b) Both A and R are true, but R is not the correct explanation of A.

Question 11.
Assertion (A): Isotopes are electrically neutral.
Reason (R): Isotopes are species with same mass number but different atomic numbers
Answer:
(c) A is true but R is false.

Question 12.
Assertion (A): Atom is electrically neutral.
Reason (R): A neutral particle, neutron, is present in the nucleus of atom.
Answer:
(b) Both A and R are true, but R is not the correct explanation of A.

Question 13.
Assertion (A): The size of the nucleus is very small as compared to the size of the atom.
Reason (R): The electrons revolve around the nucleus of the atom
Answer:
(b) Both A and R are true, but R is not the correct explanation of A.

Question 14.
Assertion (A): Isobars are identical in chemical properties.
Reason (R): Isobars have same atomic number.
Answer:
(d) A is false but R is true.

Journey Inside the Atom Class 9 Fill in the Blanks

1. Atoms are made up of smaller particles called ……………………….. .
Answer:
subatomic particles

2. The combining capacity of an atom is known as its ………………………. .
Answer:
valency

3. Chlorine occurs in nature in ………………………… isotopic forms.
Answer:
two

4. …………………………… are the building blocks of matter.
Answer:
Atoms

5. The maximum number of electrons that can be present in the L-shell is ………………………. .
Answer:
eight

6. The shells of an atom are also called ………………….. levels.
Answer:
energy

7. The formula used to find the maximum number of electrons in a shell is ………………….. .
Answer:
2n²

8. The number of protons in an atom is known as its ………………………….. .
Answer:
atomic number

9. The neutral particle present in the nucleus is called ………………………. .
Answer:
neutron

10. ………………….. is also called the planetary model of the atom.
Answer:
Rutherford’s model

Journey Inside the Atom Class 9 True or False

1. Electrons are present inside the nucleus.
Answer:
False

2. Rutherford’s model explained the stability of the atom.
Answer:
False

3. Protons and neutrons together are called nucleons.
Answer:
True

4. Bohr proposed that electrons move in fixed energy levels.
Answer:
True

5. Atoms with complete outer shells are generally reactive.
Answer:
False

6. The mass of an atom is mainly due to electrons.
Answer:
False

7. The symbol of an element always starts with a lowercase letter.
Answer:
False

8. Protons are heavier than electrons.
Answer:
True

9. The atomic number is equal to the number of protons.
Answer:
True

10. Electrons carry a positive charge.
Answer:
False

Journey Inside the Atom Class 9 Match the Following

Question 1.
Match the Column A with Column B.

Column A	Column B
(i) Dalton	(a) Energy levels
(ii) Thomson	(b) Indivisible atom
(iii) Rutherford	(c) Plum pudding model
(iv) Bohr	(d) Nuclear model

Answer:
(i) – (b), (ii) – (c), (iii) – (d), (iv) – (a)

Column A	Column B
(i) Dalton	(b) Indivisible atom
(ii) Thomson	(c) Plum pudding model
(iii) Rutherford	(d) Nuclear model
(iv) Bohr	(a) Energy levels

Question 2.
Match the Column A with Column B.

Column A	Column B
(i) Fe	(a) Sodium
(ii) Na	(b) Iron
(iii) K	(c) Silver
(iv) Ag	(d) Potassium

Answer:
(i) – (b), (ii) – (a), (iii) – (d), (iv) – (c)

Column A	Column B
(i) Fe	(b) Iron
(ii) Na	(a) Sodium
(iii) K	(d) Potassium
(iv) Ag	(c) Silver

Question 3.
Match the electron distributions with the elements.

Column A	Column B
(A) Hydrogen	(1) 2, 8, 8
(B) Oxygen	(2) 2, 6
(C) Magnesium	(3) 1
(D) Argon	(4) 2, 8, 2

(a) A – 1, B – 2, C – 3, D – 4
(b) A – 2, B – 3, C – 4, D – 1
(c) A – 3, B – 2, C – 4, D – 1
(d) A – 4, B – 1, C – 2, D – 3
Answer:
(c) A – 3, B – 2, C – 4, D – 1

Column A	Column B
(A) Hydrogen	(3) 1
(B) Oxygen	(2) 2, 6
(C) Magnesium	(4) 2, 8, 2
(D) Argon	(1) 2, 8, 8

Question 4.
Match the energy levels with their electron capacities.

Column A	Column B
(A) K-shell	(1) 32 electrons
(B) L-shell	(2) 2 electrons
(C) M-shell	(3) 8 electrons
(D) N-shell	(4) 18 electrons

(a) A – 1, B – 2, C – 3, D – 4
(b) A – 2, B – 3, C – 4, D – 1
(c) A – 3, B – 4, C – 1, D – 2
(d) A -4, B – 1, C – 2, D – 3
Answer:
(b) A – 2, B – 3, C – 4, D – 1

Column A	Column B
(A) K-shell	(2) 2 electrons
(B) L-shell	(3) 8 electrons
(C) M-shell	(4) 18 electrons
(D) N-shell	(1) 32 electrons

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