10)An unsaturated hydrocarbon weighing 1.68 gm has volume of 488 ml at S.T.P. If it contains 14% of hydrogen, then the family to which the hydrocarbon belongs is alkane alkene alkyl benzene

To answer this question, we need to follow these steps:

Step 1: Calculate the molecular weight of the hydrocarbon. We know that 1 mole of any gas at STP occupies 22.4 L or 22400 mL. So, the molecular weight of the hydrocarbon can be calculated as follows:

(Weight of the hydrocarbon / Volume of the hydrocarbon at STP) * Volume of 1 mole of gas at STP = (1.68 gm / 488 mL) * 22400 mL = 77.7 gm/mol

Step 2: Calculate the weight of carbon in the hydrocarbon. We know that the hydrocarbon contains 14% of hydrogen, so it must contain 86% of carbon. Therefore, the weight of carbon in the hydrocarbon is:

Weight of the hydrocarbon * Percentage of carbon = 1.68 gm * 0.86 = 1.44 gm

Step 3: Calculate the number of moles of carbon in the hydrocarbon. We know that the atomic weight of carbon is 12 gm/mol. So, the number of moles of carbon in the hydrocarbon is:

Weight of carbon / Atomic weight of carbon = 1.44 gm / 12 gm/mol = 0.12 mol

Step 4: Calculate the number of moles of hydrogen in the hydrocarbon. We know that the hydrocarbon contains 14% of hydrogen, so the weight of hydrogen in the hydrocarbon is:

Weight of the hydrocarbon * Percentage of hydrogen = 1.68 gm * 0.14 = 0.2352 gm

We also know that the atomic weight of hydrogen is 1 gm/mol. So, the number of moles of hydrogen in the hydrocarbon is:

Weight of hydrogen / Atomic weight of hydrogen = 0.2352 gm / 1 gm/mol = 0.2352 mol

Step 5: Determine the empirical formula of the hydrocarbon. The empirical formula of a compound is the simplest whole number ratio of atoms in the compound. In this case, the empirical formula of the hydrocarbon is:

C0.12H0.2352

To convert this to whole numbers, we divide each subscript by the smallest subscript, which is 0.12:

C(0.12/0.12)H(0.2352/0.12) = CH2

Step 6: Determine the molecular formula of the hydrocarbon. We know that the molecular weight of the hydrocarbon is 77.7 gm/mol. The molecular weight of the empirical formula (CH2) is 14 gm/mol. So, the number of empirical formula units in the molecular formula is:

Molecular weight of the hydrocarbon / Molecular weight of the empirical formula = 77.7 gm/mol / 14 gm/mol = 5.55

Since the number of empirical formula units in the molecular formula must be a whole number, we round 5.55 to the nearest whole number, which is 6. Therefore, the molecular formula of the hydrocarbon is:

(CH2)6 = C6H12

Step 7: Determine the family to which the hydrocarbon belongs. The general formula for alkanes is CnH2n+2, for alkenes is CnH2n, and for alkynes is CnH2n-2. The molecular formula of the hydrocarbon (C6H12) matches the general formula for alkenes (CnH2n). Therefore, the hydrocarbon belongs to the alkene family.