What is the value of $x$ if $2x + 5 = 15$?

Which one of the following metallic hydroxides does not dissolve in sodium hydroxide solution?

What is common between chloroplasts,chromoplasts and leucoplasts?

Match List-$I$ with List-$II$ and then select the correct answer from the codes given below the lists:

List-$I$	List-$II$
$A$. Butane $\to$ Isobutane	$a$. Cracking
$B$. Butane $\to$ Lower hydrocarbons	$b$. Isomerisation
$C$. $n$-Heptane $\to$ Toluene	$c$. Reed reaction
$D$. Propane $\to$ $CH_3CH_2CH_2SO_2Cl$	$d$. Aromatisation

In which of the following compounds does the transition metal have a zero oxidation state?

For a gas,$\frac{R}{C_{v}}=0.4$,where $R$ is the universal gas constant and $C_{v}$ is the molar specific heat at constant volume. The gas is made up of molecules which are