Consider the isomers of hydrocarbon with molecular formula \( \text{C}_5\text{H}_{10} \). These isomers do not decolourise \( \text{KMnO}_4 \) solution. These isomers are subjected to chlorination with chlorine in presence of light to give monochloro compounds. The total number of monochloro compounds (structural isomers only) formed is ________.