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

Describe the general trends in the following properties of the elements in Groups 13 and 14.

Nature of halides

Account for the following observations:

Though fluorine is more electronegative than chlorine yet BF₃ is a weaker Lewis acid than BCl₃ 

Account for the following observations:

PbO₂ is a stronger oxidising agent than SnO₂ 

Account for the following observations:

The +1 oxidation state of thallium is more stable than its +3 state.

Three pairs of compounds are given below. Identify that compound in each of the pairs which has group 13 element in more stable oxidation state. Give reason for your choice. State the nature of bonding also.

TlCl₃, TlCl

Three pairs of compounds are given below. Identify that compound in each of the pairs which has group 13 element in more stable oxidation state. Give reason for your choice. State the nature of bonding also.

AlCl₃ , AlCl

Three pairs of compounds are given below. Identify that compound in each of the pairs which has group 13 element in more stable oxidation state. Give reason for your choice. State the nature of bonding also.

InCl₃, InCl

BCl₃ exists as monomer whereas AlCl₃ is dimerised through halogen bridging. Give reason. Explain the structure of the dimer of AlCl₃ also.

Boron fluoride exists as BF₃ but boron hydride doesn’t exist as BH₃. Give reason. In which form does it exist? Explain its structure.

A nonmetallic element of group 13, used in making bullet proof vests is extremely hard solid of black colour. It can exist in many allotropic forms and has unusually high melting point. Its trifluoride acts as Lewis acid towards ammonia. The element exihibits maximum covalency of four. Identify the element and write the reaction of its trifluoride with ammonia. Explain why does the trifluoride act as a Lewis acid.

Name the compounds whose line formulae are given below:

Name the compounds whose line formulae are given below:

Write structural formulae for compounds named as-

1-Bromoheptane

Write structural formulae for compounds named as-

5-Bromoheptanoic acid

Which of the following gases is not a green house gas?

The gaseous envelope around the earth is known as atmosphere. The lowest layer of this is extended upto 10 km from sea level, this layer is ______.

The acids present in acid rain are:

(i) Peroxyacetylnitrate

(ii) H₂CO₃ 

(iii) HNO₃

(iv) H₂SO₄ 

Green house effect leads to global warming. Which substances are responsible for green house effect?

Acid rain is known to contain some acids. Name these acids and where from they come in rain?

Some time ago formation of polar stratospheric clouds was reported over Antarctica. Why were these formed? What happens when such clouds break up by warmth of sunlight?