Cyclic hydrocarbon molecule A has all the carbon and hydrogen in a single plane. All the carbon-carbon bonds are of same length and less that 1.54 $\stackrel{0}{\mathrm{A}}$ but more than 1.34 $\stackrel{0}{\mathrm{A}}$. C - C - C bond angle will be

Cyclic hydrocarbon in which all the carbon atoms are present in the same plane is benzene. In this C - C bond length is 1.39$\stackrel{0}{\mathrm{A}}$ which is more than 1.34$\stackrel{0}{\mathrm{A}}$ but less than 1.54$\stackrel{0}{\mathrm{A}}$ Hence bond angle is 120° with sp² hybridization.