Question

When cyclohexane is poured on water, it floats because;
A) Cyclohexane is in a ‘boat’ form.
B) Cyclohexane is in a ‘chair’ form.
C) Cyclohexane is in a ‘crown’ form.
D) Cyclohexane is less dense than water.

Answer 1

Hint: Floating capacity of a substance depends upon the density of the substance. The substance will float if it is less dense than water. Any object placed in a fluid a receives an upward force, due to the pressure at the depth.

Complete answer:
A substance will float in water if it is less dense than water. This is the common fact related with the ability of a substance to float in water.
Here we have the compound cyclohexane with us.
We know that it is an alkane, a hydrocarbon. They are formed by the covalent bond formation of a carbon atom with mainly four hydrogen atoms or with three hydrogen atoms and with an adjacent carbon atom and this chain will continue. A carbon atom has valency as four and it cannot gain or lose electrons. So, it only shares its electrons and thereby it creates a separate group of compounds in Chemistry which are known as organic compounds.
Here we are discussing hydrocarbons. The name itself shows that the compound contains mainly carbon and hydrogen atoms. Also, the word ‘cyclo’ mentions that the structure of the compound includes a cyclic ring. Normal hexane is a straight chain compound and cyclohexane is a cyclic compound. It’s structure will be like this;

Usually alkanes are less dense than water and most of them have the ability to float in water. This ability is irrespective of their structure whether it is cyclic or it is a normal chain or it is a ‘boat’ or ’chair’ etc.
Therefore, the reason behind the ability of cyclohexane to float in water is because of its less density than water.

Hence, the correct answer is option D.

Additional information:
Alkanes are mainly colourless substances. They are non-polar molecules and are more soluble in non-polar solvents than in polar solvents because of the fact that ‘like dissolves like’.

Note: Alkanes are hydrocarbons formed by the covalent bond formation of carbon with hydrogen. They are less dense than water. These are the most basic part of the all organic compounds but it undergoes very few reactions like combustion and halogenation.