[2 Mark Question Answer]

Question 12 Marks

State its one drawback of Rutherford’s atomic model.

Answer

Rutherford’s atomic model could not explain the stability of the atom as it is like a solar system, the sun is at the centre and the planets revolve around it, in an atom the electrons revolve around the centrally located nucleus containing protons.

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Question 22 Marks

Draw the diagrams representing the atomic structures of the following : Neon

Answer

Neon ${ }_{10}^{20} \ \mathrm{Ne}$

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Question 32 Marks

Draw the diagrams representing the atomic structures of the following : Nitrogen.

Answer

Nitrogen ${ }_7^{14} \mathrm{~N}$

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Question 42 Marks

The atomic number and the mass number of sodium are $11$ and $23$ respectively. What information is conveyed by this statement.

Answer

Atomic number $= 11$; No of protons $= 11$
Mass number $= 23 =$ Number of protons $+$ Number of neutrons.
No of neutrons $= 23-11 = 12$.

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Question 52 Marks

What is variable valency? Name two elements having variable valency and state their valencies.

Answer

Variable valency: Some elements exhibit more than one valency. They are said to have variable valency, e.g. Iron, copper, tin, lead.
Iron Fe $Fe^{2+}$ or $Fe^{3+}$
Copper cu $cu^+$ or $cu^{2+}$

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