Science (English Medium) कक्षा ११ - CBSE Question Bank Solutions for Chemistry

Ozone is a toxic gas and is a strong oxidising agent even then its presence in the stratosphere is very important. Explain what would happen if ozone from this region is completely removed?

On the basis of chemical reactions involved, explain how do chlorofluorocarbons cause thinning of ozone layer in stratosphere.

How is ozone produced in stratosphere?

Ozone is a gas heavier than air. Why does ozone layer not settle down near the earth?

Assertion (A): Ozone is destroyed by solar radiation in upper stratosphere.

Reason (R): Thinning of the ozone layer allows excessive UV radiations to reach the surface of earth.

Indicate the σ and π bonds in the following molecule:

\[\ce{HCONHCH3}\]

Pressure is determined as force per unit area of the surface. The SI unit of pressure, Pascal is as shown below:-
1Pa = 1N m^–2
If mass of air at sea level is 1034 g cm^–2, calculate the pressure in Pascal.

What is the SI unit of mass? How is it defined?

Write the atomic number of the element present in the third period and a seventeenth group of the periodic table.

Use the periodic table to answer the following question.

Identify an element with five electrons in the outer subshell.

Use the periodic table to answer the following question.

Identify an element that would tend to lose two electrons.

Use the periodic table to answer the following question.

Identify an element that would tend to gain two electrons.

Use the periodic table to answer the following question.

Identify the group having metal, non-metal, liquid as well as gas at room temperature.

Assign the position of the element having an outer electronic configuration in the periodic table.

ns² np⁴ for n = 3

Assign the position of the element having an outer electronic configuration in the periodic table.

(n - 1)d² ns² for n = 4

Assign the position of the element having an outer electronic configuration in the periodic table.

(n - 2) f⁷ (n - 1)d¹ ns² for n = 6

Electromagnetic radiation of wavelength 242 nm is just sufficient to ionise the sodium atom. Calculate the ionisation energy of sodium in kJ mol^–1.

The diameter of zinc atom is 2.6 Å. Calculate

1. radius of zinc atom in pm and
2. number of atoms present in a length of 1.6 cm if the zinc atoms are arranged side by side length-wise.

Write reactions to justify amphoteric nature of aluminium.

What happens when Borax is heated strongly.