Answer:
A small amount of solute dissolved in a larger amount of solvent.
Take this analogy to help you understand, if you were to put a teaspoon of sugar in a liter of water it would dissolve, but if you put a sack of sugar in it it would not dissolve! The solute is what is being dissolved and the solvent is what dissolves the solute, so that eliminates some of the options.
Data:
solute: ethylene glicol => not ionization
molar mass of ethylene glicol (from internet) = 62.07 g/mol
solute = 400 g
solvent = water = 4.00 kg
m =?
ΔTf = ?
Kf = 1.86 °C/mol
Formulas:
m: number of moles of solute / kg of solvent
ΔTf = Kf*m
number of moles of solute = mass in grams / molar mass
Solution
number of moles of solute = 400 g / 62.07 g/mol = 6.44 moles
m = 6.44 mol / 4 kg = 1.61 m <-------- molality (answer)
ΔTf = 1.86 °C / m * 1.61 m = 2.99 °C <---- lowering if freezing point (answer)
Answer: Half-life of the substance is 16 years.
Explanation:
Expression for rate law for first order kinetics is given by:
where,
k = rate constant
t = age of sample = 48 years
a = initial amount of the reactant = 240 micrograms
a - x = amount left after decay process = 30 microgarms
b) 
of reaction
Thus half-life of the substance is 16 years.
