Balbharati Class 8 General Science Solutions Inside the Atom

Welcome to NCTB Solutions. Here with this post we are going to help 8th class students for the Solutions of Balbharati Class 8 General Science Book Chapter 5, Inside the Atom. Here students can easily find step by step solutions of all the questions in Inside the Atom. Also our Expert Science Teacher’s solved all the problems with easily understandable language with proper guidance so that all the students can understand easily. Here in this post students will get chapter 5 solutions. Here all the Question Answer are based on Balbharati latest syllabus. Here all the question and answer are based on Maharashtra State Board latest syllabus.

Inside the Atom Exercise question Solutions :

Question no – (1)

Answer :

(a) The difference between atomic models of Rutherford and Thomson are as follows

Thomson :

According to Thomson model there was no nucleus.

In his model the protons were distributed throughout the atom and the electrons were embedded in the atom.

It came forth in 1904.

Rutherford :

According to Rutherford nucleus was present and positively charged.

In his model the protons were present in the nucleus and the electrons revolved around the atom.

It came forth in year 1911.

(b) Valency of an element means the number of chemical bonds formed by that atom.

The relation between number of valence electrons and valency is that valency of an atom depends on the number of valence electrons it has in the outermost shell.

(c) Atomic mass number means the mass of the total number of protons and neutrons present in an atom.

Explanation : The atomic mass of carbon atom is 12 because it has 6 protons and 6 neutrons in its nucleus and the atomic number is 6 because the nucleus has 6 protons or electrons inside it.

(d) The subatomic particles means the constituents that together help in the formation of nucleus and atoms.

The three subatomic particles are as follows :

Electrons : They are present outside nucleus, carry a negative charge and has negligible mass.
Protons : They are present inside the nucleus, carry a positive charge and has a mass of 1u.
Neutrons : They are present inside the nucleus, they don’t carry any charge and has a mass of 1u.

Question no – (2)

Answer :

(a) All the mass of an atom is concentrated in the nucleus because the subatomic particles like protons and neutrons that carry weight are present in the nucleus.

(b) Atoms are electrically neutral because the total number of positively charged protons and negatively charged electrons are always the same in every atom.

(c) Atomic mass number is a whole number because it is counted using total number of protons and neutrons which are always present in whole number.

(d) Atoms are stable even though negatively charged electrons revolved around it because it is always nullified by the same number of positive protons present inside atom.

Question no – (3)

Answer :

(a) Atom : An atom is the smallest unit of matter that can retain it’s chemical identity in all the physical and chemical changes.

(b) Isotope : An Isotope is an atom of the same element having different mass numbers.

(c) Atomic number : Atomic number means the total number of protons or electrons present in an atom.

(d) Atomic mass number : Atomic mass number means the mass of the total number of protons and neutrons present in an atom.

(e) Moderator in a nuclear reactor are graphite or heavy water that can be used as a moderator to reduce the speed of neutrons.

Question no – (5)

Answer :

(a) Electron, proton, neutron are the types of Subatomic particles in an atom.

(b) An electron carries a Negative charge.

(c) The electron shell K is nearest to the nucleus