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Chemistry — STRUCTURE OF THE ATOM

50 Questions Class 9 MCQs
1
Who discovered the electron?
2
What is the charge of an electron?
3
Who discovered the proton?
4
Who discovered the neutron?
5
The mass of an electron is approximately:
6
What is the charge on a proton?
7
The nucleus of an atom contains:
8
The atomic number is equal to the number of:
9
The mass number of an atom is:
10
Isotopes are atoms of the same element having:
11
Which of the following is an isotope of hydrogen?
12
Who proposed the planetary model of the atom?
13
The nucleus was discovered by:
14
In Rutherford’s model, most alpha particles passed straight through the foil because:
15
Bohr’s model explains:
16
The lowest energy level of an atom is called:
17
Which of the following represents an isotope pair?
18
The electronic configuration of oxygen (atomic number 8) is:
19
Maximum electrons in a shell are given by:
20
The valence shell of sodium has:
21
Isobars are atoms with:
22
Example of isobars:
23
The K-shell can have a maximum of:
24
The L-shell can have a maximum of:
25
What is the atomic number of carbon?
26
The neutral atom of an element has:
27
What particle decides the charge of the atom?
28
The isotope of chlorine are in ratio 3:1, their mass numbers are:
29
The average atomic mass of chlorine is:
30
Who proposed the modern atomic model?
31
The path of electron around nucleus is called:
32
The subatomic particles present inside the nucleus are:
33
The mass of proton is approximately:
34
The nucleus is:
35
The number of neutrons in \(^{14}_6C\) is:
36
The first orbit can hold:
37
The second orbit can hold:
38
Which particle is neutral?
39
Which of the following is not an isotope of hydrogen?
40
The number of electrons in \(\mathrm{Mg^{2+}}\) (Z=12) is:
41
The charge on an alpha particle is:
42
Who proposed that electrons revolve in fixed orbits without radiating energy?
43
The valence electrons determine:
44
The formula to calculate number of neutrons is:
45
Which shell has the highest energy?
46
An atom of sodium has electronic configuration 2,8,1. It belongs to which period?
47
Electrons are arranged around nucleus according to:
48
The number of shells in chlorine (Z=17) atom is:
49
What is the valency of oxygen?
50
Which of the following is the correct electronic configuration of calcium (Z=20)?

Frequently Asked Questions

Atoms have a nucleus made of protons and neutrons, with electrons arranged in shells around it.

James Chadwick discovered the neutron in 1932.

Protons, neutrons, and electrons.

The number of protons in the nucleus of an atom.

The sum of protons and neutrons in the atom’s nucleus.

Atoms of the same element with different numbers of neutrons.

Atoms of different elements with the same mass number but different atomic numbers.

The number of electrons an atom can gain, lose, or share to become stable.

Electrons revolve in fixed orbits (shells) around the nucleus without losing energy.

Atomic number is protons; mass number is protons + neutrons.

Electrons fill shells in order, with each shell holding up to \(2n^2\) electrons.

J.J. Thomson.

The gold foil experiment.

Electrons in the outermost shell of an atom.

They have the same number of protons and electrons.

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