CBSE-2020

A compound ‘$\mathrm{X}$’ on heating with excess conc. sulphuric acid at $443 \mathrm{K}$ gives an unsaturated compound ‘$\mathrm{Y}$’. ‘$\mathrm{X}$’ also reacts with sodium metal to evolve a colourless gas ‘$\mathrm{Z}$’. Identify ‘$\mathrm{X}$’, ‘$\mathrm{Y}$’ and ‘$\mathrm{Z}$’. Write the equation of the chemical reaction of formation of ‘$\mathrm{Y}$’ and also write the role of sulphuric acid in the reaction.

Why are most carbon compounds poor conductors of electricity?

Write the name and structure of a saturated compound in which the carbon atoms are arranged in a ring. Give the number of single bonds present in this compound.

What is a homologous series of carbon compounds ? Give an example and list its three characteristics.

Write the molecular formula of ethene and draw its electron dot structure.

Incomplete combustion of coal and petroleum:

(A) increases air pollution.

(B) increases efficiency of machines.

(C) reduces global warming.

(D) produce poisonous gases.

The correct option is:

$3 \mathrm{mL}$ of ethanol is taken in a test tube and warmed gently in a water bath. A $5 \%$ solution of alkaline potassium permanganate is added first, drop by drop to this solution, then in excess.

• How is $5 \%$ solution of ${\mathrm{KMnO}}_4$ prepared?
• State the role of alkaline potassium permanganate in this reaction. What happens on adding it in excess?
• Write a chemical equation of this reaction.

Name a cyclic unsaturated carbon compound.