A) a water sample (density=1.00g/ml, s=0.28g/kg) contains ca(2+) at a concentration of 42 mg/kg. calculate the molarity of the ion.

Answer : The molarity of the ion is

Explanation : Given,

Density of sample = 1.00 g/mL

Concentration of = 42 mg/kg

First we have to calculate the volume of sample.

Let us assume that the mass of sample be 1 kg or 1000 g.

       (1 L = 1000 mL)

Now we have to calculate the moles of

As we are given that,

Mass of in 1 kg of sample = 42 mg = 0.042 g

Molar mass of Ca = 40 g/mole

Now we have to calculate the molarity of the ion.

Therefore, the molarity of the ion is

the answer is b & c i believe : )