Answer
(a)
$$x_{C_7H_{16}} = 0.187$$
$$x_{C_8H_{18}} = 0.427$$
$$x_{C_9H_{20}} = 0.386$$
(b)
$$Mole \space percent \space {C_7H_{16}}=18.7\%$$
$$Mole \space percent \space C_8H_{18}= 42.7\%$$
$$Mole \space percent \space C_9H_{20}= 38.6\%$$
Work Step by Step
(a)
$$x_{C_7H_{16}} = \frac{1.28 }{1.28 + 2.92 + 2.64} = 0.187$$
$$x_{C_8H_{18}} = \frac{2.92 }{1.28 + 2.92 + 2.64} = 0.427$$
$$x_{C_9H_{20}} = \frac{2.64 }{1.28 + 2.92 + 2.64} = 0.386$$
(b)
$$Mole \space percent \space {C_7H_{16}} = \frac{1.28 }{1.28 + 2.92 + 2.64} \times 100\% = 18.7\%$$
$$Mole \space percent \space = \frac{2.92 }{1.28 + 2.92 + 2.64} \times 100\% = 42.7\%$$
$$Mole \space percent \space = \frac{2.64 }{1.28 + 2.92 + 2.64} \times 100\%= 38.6\%$$
