p-Block Elements-I 2 Question 15
15. With respect to graphite and diamond, which of the statement(s) given below is/are correct?
(2012)
(a) Graphite is harder than diamond
(b) Graphite has higher electrical conductivity than diamond.
(c) Graphite has higher thermal conductivity than diamond.
(d) Graphite has higher $\mathrm{C}-\mathrm{C}$ bond order than diamond
Assertion and Reason
(a) Statement I is correc;t Statement II is correct Statement II is the correct explanation of Statement I
(b) Statement I is correct; Statement II is correct Statement II is not the correct explanation of Statement I
(c) Statement I is correct; Statement II is incorrect
(d) Statement I is incorrect; Statement II is correct
Show Answer
Solution:
- Diamond has a three-dimensional network structure, a hard substance where graphite is soft due to layered structure. In graphite, only three valence electrons are involved in bonding and one electron remain free giving electrical conductivity. In diamond, all the four valence electrons are covalently bonded hence, insulator.
Diamond is better thermal conductor than graphite. Electrical conductivity is due to availability of free electrons, thermal conduction is due to transfer of thermal vibrational energy from one atom to another atom. A compact and precisely aligned crystals like diamond thus facilitate better movement of heat.
In graphite $\mathrm{C}-\mathrm{C}$ bond acquire some double bond character, hence, higher bond order than in diamond.
