1. ASSERTION AND REASONING QUESTIONS:

In the following questions, a statement of assertion (A) is followed by a statement of reason (R).

Mark the correct choice as:

(a) Both assertion (A) and reason (R) are true, and reason (R) is the correct explanation of

assertion (A).

(b) Both assertion (A) and reason (R) are true, but reason (R) is not the correct explanation of

assertion (A).

(c) Assertion (A) is true, but reason (R) is false. (d) Assertion (A) is false, but reason (R) is true

1) Assertion: Atom is electrically neutral.

Reason: A neutral particle, neutron is present in the nucleus of atom.

2) Assertion: Maximum number of electrons that can be accommodated in L-shell is 8 Reason: The formula to find maximum number of electrons in a shell is 2n2.

3) Assertion: For noble gases, valency is zero.

Reason: Noble gases have 8 valence electrons

4)Assertion: The Nitrogen atom loses its 3 valence electrons to form its ion Reason: Nitrogen ion is an anion

II CHOOSE THE CORRECT ANSWER:

1.An atom has 4 electrons and 4 protons and 4 neutrons. The atom is electrically neutral.

Which difference in the properties of protons and electrons affects the electrical neutrality (c) Electrons and protons have opposite charges of the same magnitude

of the atom?

(a)Electrons are 2000 times lighter than protons.

(b) Electrons and protons have the same charge and mass.

(d) Electrons are present in the outer side of the atom compared to the protons..

An atom is neutral because it contains an equal number of protons and electrons. Though the atom actually contains neutrons, this reason does not explain the electrical neutrality of the atom.

The L shell actually contains eight electrons because the maximum number of electrons accommodated in each shell is given by 2n^2 where n is the principal quantum number. Since the L-shell corresponds to n=2 then the reason is the correct explanation of the assertion.

The valency of atoms is determined by the number of electrons in the outermost shell of the atom. Remember that atoms having a filed valence shell(eight electrons in the outermost shell) have a valency of zero. Hence the noble gases possess a zero valency. Thus the reason is the correct explanation of the assertion.

Nitrogen forms its ion by electron gain and not by electron loss because nitrogen forms an anion. This anion is formed by a gain of three electrons. The assertion is false but the reason is true.