Graphite

Q.

Thermodynamically the most stable form of carbon is
(a) diamond (b) graphite
(c) fullerenes (d) coal

Q.

In the following questions a statement of Assertion (A) followed by a statement of Reason (R) is given. Choose the correct answer out of the following choices.

(a) Assertion and Reason both are correct statements an Reason is correct explanation for Assertion.

(b) Assertion and Reason both are correct satements but Reason is not correct explanation for Assertion.

(c) Assertion is correct statement but Reason is wrong statement

(d) Assertion is wrong statement but Reason is correct statement.

Assertion (A) Graphite is a good conductor of electricity however diamond belongs to the category of insulators.

Reason (R) Graphite is soft in nature on the other hand diamond is very hard and brittle.

Q.

Which allotrope of carbon conducts electricity?

Q.

Classify the following as amorphous or crystalline solids:

Polyurethane, naphthalene, benzoic acid, teflon, potassium nitrate, cellophane, polyvinyl chloride, fibre glass, copper.

Q.

The total number of $\mathrm{C}–\mathrm{C}$ sigma bond/s in mesityl oxide $\left({\mathrm{C}}_6{\mathrm{H}}_{10}\mathrm{O}\right)$ is

Q. In graphite, electrons are:

1. Localized on each carbon atom
2. Spread out between the structure
3. localized on every third carbon atom
4. present in antibonding orbital

Q.

What are the electrodes used in the extraction of aluminium?

Q.

Buckminsterfullerene is an allotropic form of

1. Phosphorus

2. Sulfur

3. Carbon

4. Tin

Q.

With respect to graphite and diamond, which of the statement(s) given below is/are correct?

1. Graphite is harder than diamond

2. Graphite has a higher electrical conductivity than diamond

3. Graphite has a higher thermal conductivity than diamond

4. Graphite has a higher C – C bond order than diamond

Q.

Why is there no charge on carbene, even though the carbon atom has a lone pair?

Q. Graphite conducts electricity because of

1. Weak Vander Waal's forces between layers
2. Covalent bonding between carbon atoms of layers
3. Delocalized electrons in each layer
4. $s{p}^2$ hybridisation of carbon atoms in a layer

Q. Graphite is a good conductor of electricity because:

1. has tetra hedral structure
2. has free electrons
3. is crystalline
4. has free atoms

Q. Difference between diamond and graphite is due to -

1. Graphite combines with oxygen to form carbon dioxide but diamond does not.
2. The atoms in each have different masses
3. The crystal structure in diamond is different from that in graphite
4. All

Q. Diamond has each of the following properties except

1. high melting point
2. ability to conduct electricity
3. Inertness to chemicals
4. Extreme hardness

Q. Graphite is a conductor.Though it is a covalent solid.It also has no free electrons in atoms of its structure.

Q.

The number of pi electrons present in naphthalene is

1. $6$

2. $10$

3. $5$

4. $12$

Q. Which allotropic form of carbon is thermodynamically the most stable ?

1. Diamond
2. Graphite
3. Fullerenes
4. Coal

Q.

The lead of pencil is made by mixing clay with powdered ______

Q. Graphite is a good conductor of heat and electricity because it contains :

1. layers of carbon atoms.
2. sheet like structure.
3. $p\pi -p\pi$ bonding.
4. free electrons.

Q.

Graphite is soft solid lubricant extremely difficult to melt. The reason for this anomalous behavior is that graphite:

1. has molecules of variable molecular masses like polymers

2. is a non-crystalline substance

3. has carbon atoms arranged in large plates of rings of strongly bound carbon atoms with weak interpolate bonds

4. is an allotropic form of diamond

Q.

Complete the following sentences:

When a diamond is heated at about 1600^oC in the absence of oxygen, it is ………

Q.

Name the source rock of diamond.

Q. Choose the correct option:
Assertion: $AlC{l}_3$ forms a dimer but $BC{l}_3$ does not form a dimer.
Reason: $AlC{l}_3$ does not exhibit back bonding because of large size of aluminum.

Q. 14. The decomposition of phosphine on tungsten at law pressure is a first order rxn.it is because the 1)rate is proportional to surface coverage 2)rate is inversely proportional to surface coverage 3)rate is independent of surface coverage 4)rate of decomposition is very slow

Q. Graphite is used as lubricant due to :

1. The slippery nature
2. Its giant structure
3. High refractive index
4. High IP value of carbon

Q.

Give a reason for the following

A graphite anode is preferred to another inert electrode during electrolysis of fused lead bromide.

Q. Lead pencil is made up of lead metal.

1. True
2. False

Q.

Where is diamond found?

Q. Though both diamond and graphite are purest forms of carbon only graphite can conduct electricity. Explain.

Q. Assertion :Diamond is a bad conductor of electricity. Reason: There are no free electrons in it.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct