Since, the hydrocarbon `(C_8H_18)` on monochlorination gives a single monochloride , therefore , all the 18 H-atoms are equivalent. The only such hydrocarbon is 2,2,3,3-tetramethylbutane , i.e., `CH_3-undersetunderset(CH_3)|oversetoverset(CH_3)|C-undersetunderset(CH_3)|oversetoverset(CH_3)|C-CH_3`