Lakhmir Singh & Manjit Kaur Test: Structure of the Atom


25 Questions MCQ Test NCERT Hindi Textbooks (Class 6 to Class 12) | Lakhmir Singh & Manjit Kaur Test: Structure of the Atom


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QUESTION: 1

The first use of quantum theory to explain the structure of atom was made by –

Solution: Bohr first made use of quantum theory to explain the structure of atom and proposed that energy of electron in an atom is quantized
QUESTION: 2

Plum-Pulding model is known as–

Solution:

Thomson proposed the plum pudding model of the atom, which had negatively-charged electrons embedded within a positively-charged "soup." Rutherford's gold foil experiment showed that the atom is mostly empty space with a tiny, dense, positively-charged nucleus.

QUESTION: 3

Nucleous consist of–

Solution:
QUESTION: 4

The number of valence electron in Na is –

Solution:

The correct option is A.
sodium is located in group 1, which means that it has 1
valence electron. This valence electron is located in sodium's third energy shell

QUESTION: 5

Mass number of element is –

Solution:

The mass number, also called atomic mass number or nucleon number, is the total number of protons and neutrons in an atomic nucleus. It is approximately equal to the atomic mass of the atom expressed in atomic mass units.

QUESTION: 6

According to the Dalton's atomic theory –

Solution:
QUESTION: 7

Neutron is a fundamental particle which have–

Solution:
QUESTION: 8

No. of unpaired electron in 1s2.2s2.2p4

Solution:

Hund's rule says , when electrons are filled in orbitals of equal energy, one electron enters each orbital until all the orbitals contain one electron with the same spin direction. Then the pairing of electrons take place.

Thus in electronic configuration, the electrons in p subshell are filled in 3 orbitals such that every orbital contains one electron each. The fourth electron will be paired up with the first electron and the other two electrons remain unpaired.

QUESTION: 9

The electron should be filled in the orbital in accordance with the increasing order of their energy. This statement
is related with

Solution:

This statement is related with Aufbau principle.
According to Aufbau principle (also known as (n+l) rule), electrons are filled in different orbitals from lower (n+l) value orbital to higher (n+l) value orbital.
In case (n+l) value is same, electron is filled first in orbital with lower value of n.

QUESTION: 10

Which species does not contain neutron –

Solution:
QUESTION: 11

In an atom, the mass number of an atom is equal to the number of___________.

Solution:
QUESTION: 12

Atomic number of any element–

Solution:

Atomic number = number of protons. 

Each proton has unit positive charge and hence, electrical charge of the nucleus is equal to the atomic number of the element.

QUESTION: 13

Lighest particle is –

Solution:
QUESTION: 14

Fundamental particle of atomic nucleus is–

Solution:

The correct option is C.
The nucleus of an atom is made up of protons and neutrons (two types of baryons) joined by the nuclear force. These baryons are further made up of sub-atomic fundamental particles known as quarks joined by the strong interaction.

QUESTION: 15

The atomic size of atom is nearly –

Solution:

The correct option is D.
The atomic size is of the order of 10−8
cm or 10−10 m or one angstrom unit.
On the other hand, the radius of an atomic nucleus is of the order of 10−13
cm or 10−15 m or one Fermi unit.

QUESTION: 16

An atom which has a mass number of 14 or 8 neutrons is–

Solution:

Isotopes are the atoms of the same element with similar atomic number but different atomic mass.The elements of isotopes share same chemical properties but different physical properties

QUESTION: 17

Electronic configuration of p in ground state is –

Solution:

The ground state electron configuration of ground state gaseous neutral phosphorus is [Ne]. 3s².3p³

QUESTION: 18

When a gas at reduced pressure is subjected to an electric discharge, the rays orignating from the negative electrode are–

Solution:

Cathode ray, stream of electrons leaving the negative electrode (cathode) in a discharge tube containing a gas at low pressure, or electrons emitted by a heated filament in certain electron tubes. Cathode rays focused on a hard target (anticathode) produce X-rays or focused on a small object in a vacuum generate very high temperatures (cathode-ray furnace). When cathode rays strike certain molecules used to coat a cathode screen, they cause the molecules (and hence the screen) to emit light.

QUESTION: 19

The maximum number of electrons that can be accomodate in the nth level is–

Solution:
QUESTION: 20

Isotopes of an element are the atom which have –

Solution:
QUESTION: 21

The nucleus of an atom contains:

Solution:
QUESTION: 22

What is the no. of electrons in Argon?

Solution:

The no. of electrons is the atomic number of an element.

QUESTION: 23

The isotope deuterium of hydrogen has

Solution:

The correct option is D.
 Hydrogen is one of two stable isotopes of hydrogen (the other being protium, or hydrogen-1). The nucleus of a deuterium atom, called a deuteron, contains one proton and one neutron, whereas the far more common protium has no neutrons in the nucleus.

QUESTION: 24

The no. of electrons in the valence shells of Sodium and Calcium repectively:

Solution:

Electronic configuration of

Na is 2, 8, 1

Ca is 2, 8, 8, 2

QUESTION: 25

The maximum number of electrons that can be accommodated in third shell ( n = 3) is:

Solution: