Question

Graphite is used in pencils. It leaves a black trace of writing on paper because it consists of layers of carbon atoms that:

• A. Are wound inside, like a long thread
• B. Are attracted by paper material
• C. Fall easily
• D. Slide over each other

Answer 1

The correct option is D

Slide over each other

Explanation of Correct answers:-

Option (D) Slide over each other

• Carbon layers of graphite are linked by Van der Waal forces.
• Graphite cleans easily between the layers for which it is very soft and slippery.
• This is the reason why it is used in pencils and as lubricants in machines running at high temperatures.

Explanation of incorrect answers:-

Option (A) are wound inside, like a long thread

• Carbon atoms are arranged in a layered structure in the graphite rather than in a long thread-like manner.
• Hence, option A is the incorrect answer.

Option (B) are attracted by paper material

• There is no force of attraction between paper material and carbon atoms.
• Hence, option B is the incorrect answer.

Option (C) fall easily

• Carbon atoms are held together in a covalent bond and do not fall easily from the compound.
• Hence, option C is the incorrect answer.

Therefore, graphite is used in pencils. It leaves a black trace of writing on paper because it consists of layers of carbon atoms that slide over each other, option (D) is correct.