Answer is: molar mass of xylene 106,18 g/mol.
m(xylene) = 7,94 g.
m(cyclohexane) = 132,5 g.
T (solution) = - 4,9 °C.
Tf(cyclohexane) = 6,5 °C, frezing point.
Kf(cyclohexane) = 20,2 K·kg/mol; cryoscopic constant.
ΔT(solution) = 6,5°C - (-4,9°C) = 11,4°C = 11,4 K.
M(xylene) = Kf · m(xylene) ÷ m(cyclohexane) · ΔT(solution).
M(xylene) = 20,2 K·kg/mol · 7,94 g ÷ 0,1325 kg · 11,4 K.
M(xylene) = 106,18 g/mol.
Answer: 
for the given reaction is 130.19kJ/mol
Explanation:
To Calculate the , we use the formula:
For the given chemical reaction:
We are given:
Now, to calculate , we put the values in the above equation:
As, the value of 
comes out to be positive, the reaction is said to be non-spontaneous reaction.
Closer is bigger................
Answer is: mass oxygen is 129,28 grams.
Chemical reaction: 2C₁₈H₃₈ + 55O₂ → 36CO₂ + 38H₂O.
m(C₁₈H₃₈) = 37,5 g.
n(C₁₈H₃₈) = m(C₁₈H₃₈) ÷ M(C₁₈H₃₈).
n(C₁₈H₃₈) = 37,5 g ÷ 254 g/mol.
n(C₁₈H₃₈) = 0,147 mol.
From chemical reaction: n(C₁₈H₃₈) : n(O₂) = 2 : 55.
n(O₂) = 4,04 mol.
m(O₂) = 4,04 mol · 32 g/mol.
m(O₂) = 129,28 g.
