NCERT Class-9 Science Solutions: Chapter 4-Structure Of The Atom Part 5

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Question 25:

Write down the electron distribution of chlorine atom. How many electrons are there in the L shell? (Atomic number of chlorine is 17).

Answer:

2, 8, 7. The L shell has eight electrons

Image of electron distribution of chlorine atom.

Image of Electron Distribution of Chlorine Atom.

Image of electron distribution of chlorine atom.

Question 26:

In the atom of an element X, 6 electrons are present in the outermost shell. If it acquires noble gas configuration by accepting requisite number of electrons, then what would be the charge on the ion so formed?

Answer:

Question 27:

What information do you get from the Fig, about the atomic number, mass number and valency of atoms X, Y and Z? Give your answer in a tabular form.

Result for atomic number, mass number and valency of atoms

Atomic Number, Mass Number and Valency of Atoms

Result for atomic number, mass number and valency of atoms

Answer:

Atomic Number, Mass Number and Valency of Atoms.
Atomic number, mass number and valency of atoms.

Atomic No.

Mass No.

Valency

X.

5

11

3

Y.

8

18

2

Z.

15

31

3, 5

Question 28:

In response to a question, a student stated that in an atom, the number of protons is greater than the number of neutrons, which in turn is greater than the number of electrons. Do you agree with the statement? Justify your answer.

Answer:

No, the statement is incorrect. In an atom the number of protons and electrons is always equal.

Question 29:

Calculate the number of neutrons present in the nucleus of an element X which is represented as

Answer: