Which of the following statements is not correct regarding the gas evolved by the reaction of dilute HCl on $\mathrm{CaCO}_3$ ?

Observe the following statements

Statement I The carbon containing components of photochemical smog are acrolein, methanal and PAN. Statement II The number of greenhouse gases in the list given below is 5 .

$$ \mathrm{CH}_4, \mathrm{CO}_2, \mathrm{NO}, \mathrm{H}_2 \mathrm{O}(l), \mathrm{H}_2 \mathrm{O}(g), \mathrm{O}_2, \mathrm{O}_3 $$

The correct answer is

The condensed, bond line and complete formulae of $n$-butane are respectively.

' $X$ ' is the isomer of $\mathrm{C}_6 \mathrm{H}_{14}$. It has four primary carbons and two tertiary carbons, ' $X$ ' can be prepared from which of the following reactions?