Buckminsterfullerence is a spherical molecule in which 60 carbon atoms are arranged in interlocking hexagonal and pentagonal rings of carbon atoms. (a) How many hexagons of carbon atoms are present in one molecule of buckministerfullerene?
(b) How many pentagons of carbon atoms are present in one molecule of buckministerfullerence ?

Give a reason why carbon can neither form C^{4 +} cations nor C^4— anxious, but forms covalent compounds which are bad conductors of electricity and have low melting and boiling points.

An element X which has 6 electrons in its outermost shell, require 2 electrons to complete its octet for attaining noble gas configuration. X is an essential element for the survival of all living beings. What is X?

(i) Name the bond formed when X₇¹⁴ combines with Y₉¹⁸ .

(ii) Write the chemical formula of the compound formed when X₇¹⁴ combines with Y₉¹⁸ .

What type of bond is present in F₂?

(a) Name the element E.

(b) What is allotrope A?

(c) What is allotrope B?

(d) What is allotrope C?

(e) Which allotrope is used in making jewellery?

(f) Which allotrope is used in making anode of a dry cell?

(a) What is element A?

(b) What is the gas B?

(c) Name the allotrope C.

(d) State another use of allotrope C (other than in glass cutters)

(e) Name another allotrope of element A which exists as spherical molecules.

(f) Name a yet another allotrope of element A which conducts electricity.

Diamond and graphite are the covalent compounds of carbon element (C).

What are hydrocarbons? Give examples.

State the reason why carbon can neither form C⁴⁺ cations nor C^4- anions, but forms covalent compounds. Also state reasons to explain why covalent compounds:

(a) are bad conductors of electricity?

(b) have low melting and boiling points?

Unsaturated hydrocarbons contain multiple bonds between the two C atoms and show addition reactions. Give the test to distinguish ethane from ethene.