Which of the following $C_6H_6$ compounds has a single set of structurally equivalent hydrogen atoms? The structures are labeled $I$ to $V$ as shown in the image.

Who synthesized the first organic compound,urea,in the laboratory?

Among the compounds
$(i)$ $HC \equiv C-COOH$
$(ii)$ $CH_2=CH-COOH$
$(iii)$ $CH_3-CH_2-COOH$ and
$(iv)$ $CH_3-CH_2-OH$
The correct order of acid strength is

How many functional groups are present in the following molecule?

On mixing tetraethyl lead to gasoline available at petrol pumps,

Given below are two statements:
Statement-$I$ : Compound $(X)$, shown below, dissolves in $NaHCO_3$ solution and has two chiral carbon atoms.
Statement-$II$ : Compound $(Y)$, shown below, has two carbons with $sp^3$ hybridization, one carbon with $sp^2$ and one carbon with $sp$ hybridization.
In the light of the above statements, choose the correct answer from the options given below: