4.structure of atom

Question 1

Which aspect of Dalton’s atomic theory was proven incorrect by the discovery of electrons and protons?

Answer 1

Atoms are indivisible and indestructible

Question 2

Who was the first scientist to propose a model for the structure of an atom?

Answer 2

J.J. Thomson

Question 3

According to J.J. Thomson’s model, what analogy did he use to describe the atom’s structure?

Answer 3

(B) Christmas pudding
(C) Watermelon seeds

Question 3

Question: What are alpha (α) particles?

Answer 3

Doubly-charged helium ions

Question 4

According to Thomson’s atomic model, what is the relationship between positive and negative charges in an atom?

Answer 4

Both charges are equal in magnitude

Question 5

What was the primary objective of Rutherford’s gold foil experiment?

Answer 5

To understand how electrons are arranged within an atom

Question 6

Rutherford concluded that the positive charge in an atom is

Answer 6

Concentrated in a small region called the nucleus

Question 6

Rutherford’s nuclear model of the atom proposed that

Answer 6

Electrons revolve around the nucleus in circular paths

Question 7

Question: What was a major drawback of Rutherford’s atomic model?

Answer 7

It could not explain the stability of the atom

Question 8

Question: According to Bohr’s model, what happens to electrons when they revolve in discrete orbits?
(A) They radiate energy continuously
(B) They do not radiate energy
(C) They lose mass
(D) They merge with the nucleus

Answer 8

They do not radiate energy

Question 8

Which scientist proposed the concept of discrete orbits in the atom?

Answer 8

Neils Bohr

Question 9

Rutherford is known as the “Father” of which field

Answer 9

Nuclear Physics

Question 10

The energy levels in an atom are represented by which letters according to Bohr’s model?

Answer 10

K, L, M, N

Question 11

Who discovered the neutron

Answer 11

J. Chadwick

Question 12

Neutrons are present in the nucleus of all atoms except:
(A) Helium
(B) Carbon
(C) Hydrogen
(D) Oxygen

Answer 12

(C) Hydrogen

Question 13

The mass of an atom is primarily determined by the sum of the masses of

Answer 13

Protons and neutrons

Question 14

Question: Who proposed the rules for the distribution of electrons into different orbits of an atom?
(A) J.J. Thomson and Rutherford
(B) Bohr and Bury
(C) Dalton and Chadwick
(D) Einstein and Planck

Answer 14

(B) Bohr and Bury

Question 15

What formula is used to calculate the maximum number of electrons in a shell?
(A) 2n
(B) 2n²
(C) n²
(D) n/2

Answer 15

B) 2n²

Question 16

What is the maximum number of electrons that the K-shell can hold?

Answer 16

2

Question 17

How many electrons can the L-shell accommodate according to Bohr’s model?

Answer 17

8

Question 18

What is the maximum number of electrons that the M-shell can hold?

Answer 18

18

Question 19

According to the rules of electron distribution, what is the maximum number of electrons that can be accommodated in the outermost orbit?

Answer 19

8

Question 20

Question: According to Bohr’s distribution rule, electrons are not accommodated in a shell unless:
(A) The outermost shell is filled first
(B) The inner shells are filled
(C) There are no protons
(D) The atom is unstable

Answer 20

(B) The inner shells are filled

Question 21

What is the maximum number of electrons the N-shell can hold according to the 2n² rule?
(A) 8
(B) 18
(C) 24
(D) 32

Answer 21

(D) 32

Question 22

Q: What are the electrons present in the outermost shell of an atom called?.

Answer 22

Valence electrons

Question 23

Q: What is the term used to describe an outermost shell with eight electrons? A) Duplet B) Octet C) Sextet D) Decet

Answer 23

B) Octet

Question 23

According to the Bohr-Bury scheme, what is the maximum number of electrons that can be accommodated in the outermost shell of an atom?

Question 24

Q: What is the valency of magnesium, which has two electrons in its outermost shell? A) One B) Two C) Three D) Four

Answer 24

two

Question 24

Q: What is the primary reason why atoms react with other atoms to form molecules? A) To increase their energy B) To achieve an octet in the outermost shell C) To decrease their mass number D) To lose protons

Answer 24

B) To achieve an octet in the outermost shell

Question 25

: What is the valency of oxygen if its outermost shell contains 6 electrons? A) 2 B) 4 C) 6 D) 8

Answer 25

2

Question 25

Which of the following elements has a valency of zero? A) Chlorine B) Argon C) Sodium D) Magnesium

Answer 25

argon

Question 26

What does the atomic number (Z) of an element represent?

Answer 26

protone

Question 27

: What determines the identity of an element? A) The number of electrons in its outer shell B) The number of neutrons in the nucleus C) The number of protons in the nucleus D) The overall charge of the atom

Answer 27

C) The number of protons in the nucleus

Question 28

Q: The atoms of which element have isotopes protium, deuterium, and tritium?

Answer 28

hydrogen

Question 29

Isotopes are defined as atoms of the same element that have: A) Different numbers of protons B) Different mass numbers C) Different numbers of electrons D) Different chemical properties

Answer 29

B) Different mass numbers

Question 30

Q: An isotope of which element is used in the treatment of cancer? A) Uranium B) Iodine C) Cobalt D) Calcium

Answer 30

) Cobalt

Question 30

Q: An isotope of iodine is specifically used for the treatment of which condition? A) Cancer B) Goitre C) Diabetes D) Tuberculosis

Answer 30

B) Goitre

Question 31

Which of the following subatomic particles has the least mass? (a) Proton (b) Neutron (c) Electron (d) Alpha particle

Answer 31

(c) Electron