Science (English Medium) Class 11 - CBSE Question Bank Solutions

Indicate the σ and π bonds in the following molecule:

\[\begin{array}{cc}
\ce{HCONHCH3}
\end{array}\]

Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that?

Calculate the total number of electrons present in one mole of methane.

What is the basic theme of the organisation in the periodic table?

Define octet rule.

For the process to occur under adiabatic conditions, the correct condition is ______.

A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.

What is the initial effect of the change on vapour pressure?

A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.

How do rates of evaporation and condensation change initially?

A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.

What happens when equilibrium is restored finally and what will be the final vapour pressure?

At a certain temperature and total pressure of 10⁵ Pa, iodine vapour contains 40% by volume of I atoms

\[\ce{I2(g) <=> 2I(g)}\]

Calculate K_pfor the equilibrium.

Explain why pure liquids and solids can be ignored while writing the equilibrium constant expression?

Explain tropospheric pollution in 100 words.

Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?

List gases which are responsible for greenhouse effect.

Statues and monuments in India are affected by acid rain. How?

What would have happened if the greenhouse gases were totally missing in the earth’s atmosphere? Discuss.

How can you explain higher stability of BCl₃ as compared to TlCl₃?

Suggest reasons why the B–F bond lengths in BF₃ (130 pm) and `"BF"_4^(-)` (143 pm) differ.

Aluminium trifluoride is insoluble in anhydrous HF but dissolves on the addition of NaF. Aluminium trifluoride precipitates out of the resulting solution when gaseous BF₃ is bubbled through. Give reasons.