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

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.

What happens when Boric acid is added to water?

What happens when Aluminium is treated with dilute NaOH?

Give reason for Conc. HNO₃ can be transported in aluminium container.

Give reasons: A mixture of dilute NaOH and aluminium pieces is used to open drain.