Give reason for
(i) diamond is a covalent compound yet its melting point is very high
(ii) Diamond is used as a precious stoke.

Give reasons (iv) Diamond is used as an abrasive

Borax is an important compound of Boron. Diamond has co-valent bonding. Yet it has high melting point. Give a reason.

In the electrorefining of impure aluminium, molten AICI_3 is not used as electrolyte because : Its melting point is very high, pure aluminium formed dissolved into molten AlCl_(3) , it sublimes easily and is poor conductor due to covalent in nature, both 1 and 2

From the following statements Choose those applicable to covalent compounds. • Dissolves in organic compounds • Dissolves in water • High melting and boiling point. • Found in solid liquid and gaseous states. • Conducts electricity.

Describe giving reason which one.of the following pairs has the property indicated i. Fe or Cu has higher melting point ii. '(Co)^2+or '(Ni)^2+ has lower magnetic moment.

Which of the following statements are true? i) Starch, cellulose, resins etc are natural polymers ii) Vulcanised rubber is a semi-synthetic polymer iii) HDPE, PVC, Nylons, Polyesters etc are linear polymers iv) Linear polymérs possess relatively low density, low melting point and low tensile strength v) Amyłopectin and glycogen are naturally occuring and branched chain polymers vi) In cross linked polymers, strong covalent bonds exist between linear polymer chains . (1) Only i, ii and iii are true (2) All except iv are true (3) Only vand vi are true (4) Only i, ii, v and vi are true

A particular solid is very hard and has very high melting point. In solid state, it is a non - C0nductor and its melt is a C0nductor of electricity. Classify the solid

The characteristics of diamond and graphite, the crystalline allotropes of carbon are given. Classify them accordingly. i) Conducts electricity ii) Does not conduct electricity iii) Transparent iv) Used as a lubricant