NCERT Class-9 Science Solutions: Chapter 4-Structure Of The Atom Part 3

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Question 12:

Elements with valency 1 are

  1. Always metals

  2. Always metalloids

  3. Either metals or non-metals

  4. Always non-metals

Answer: C

Question 13:

The first model of an atom was given by

  1. N. Bohr

  2. E. Goldstein

  3. Rutherford

  4. J.J. Thomson

Answer: D

Image of J.J Thomson Atomic Model

Image of J.J Thomson Atomic Model

Image of J.J Thomson Atomic Model

Question 14:

An atom with 3 protons and 4 neutrons will have a valency of

  1. 3

  2. 7

  3. 1

  4. 4

Answer: C

Question 15:

The electron distribution in an aluminum atom is

Answer: A

Question 16:

Which of the following in Fig, do not represent Bohr’s model of an atom correctly?

Result for Bohr’s model of atom.

Bohr’S Model of Atom.

Result for Bohr’s model of atom.

  1. (i) and (ii)

  2. (ii) and (iii)

  3. (ii) and (iv)

  4. (i) and (iv)

Answer: C

Question 17:

Which of the following statement is always correct?

  1. An atom has equal number of electrons and protons.

  2. An atom has equal number of electrons and neutrons.

  3. An atom has equal number of protons and neutrons.

  4. An atom has equal number of electrons, protons and neutrons.

Answer: A

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