Qn 24.

Given below is the Bohr model of argon atom drawn by a student. If there is any mistake in the diagram ,draw the correct one.‍

(Atomic number Ar=18)

Qn 25.

Choose the pairs of isotopes from the following.

Symbols are not real

Qn 26.

Analyse the Bohr model of an atom given below and complete the table

image

Atomic Number	.....a.....
Mass number	27
No.of Protons	.....b....
No.of Electrons	.....c.....
No.of Neutrons	.....d.....

 

Qn 27.

There are 16 protons in the atom of an element. Its mass number is 32.

a) What is the atomic number of the element?

b) Write down its electronic configuration.

c) How many neutrons are present in it?

Qn 28.

The symbols  given below represent the isotopes of hydrogen

a) Name the isotopes of hydrogen.

b) Which one of them has 2 nuetrons in the nucleus of its atom?

c) Which isotope of hydrogen is used in nuclear reactors?

d) In the number of which particle do they differ from one another?

(proton, electron, neutron)

Qn 29.

Atoms of elements are made up mainly of protons,electrons and neutrons.

a) Which are the particles present in the nucleus of an atom?

b) Which one of them has a positive charge?

c) Which one of these particles has a very negligible mass?

 

Qn 30.

Atoms of elements are made up mainly of protons, electrons and neutrons.

a) Which of these particles are present in the nucleus of atoms?

b) The discovery of which particle is related to the scientist J.J.thomson?

c) Name the positively charged particles?

d) Name the scientist who proved that most of the mass of an atom is concentrated in its nucleus.

Qn 31.

 The maximum number of electrons that can be accommodated in K shell is 2 and that in L shell is 8.

a)Write down the formula used to find the maximum number of electrons that can be accommodated in any given shell

b)Find the maximum number of electrons that can be accommodated in the fourth shell of an atom.

Qn 32.

Give reason for the following.

a) There are positively charged particles and negatively charged particles in the atom of an element.But atoms are electrically neutral.

b) Most of the mass of an atom is concentrated in its nucleus.

Qn 33.

Certain findings in connection with the structure of atom are given below.Select the scientist related to each finding from the names given in bracket.

(Niels Bohr, Michael Faraday,Sir Humphrey Davy, Rutherford, J.J.Thomson)

a) Most of the mass of an atom is concentrated in its nucleus.

b) The rays originating from the cathode are made up of negatively charged particles.

c)Two types of electric charges are present in substances.

d) Electrons revolve around the nucleus in fixed paths called orbits or shells.

Qn 34.

In the atom of an element, electrons are present in three shells .The outermost shell has 7 electrons. There are 18 neutrons in the nucleus of atom.

a) Write down the electronic configuration of the given atom.

b) What is its mass number?

c) How many electrons are present in it?

Qn 35.

An atom of aluminium(Al) has 13 electrons and 14 neutrons in it.

a) What is the atomic number of aluminium?

b) What is its mass number?

c) Represent  aluminum atom  using the symbol.