A man submerges a 30g mass in an unknown liquid, giving it a mass of 20g. The gravity of unknown liquid is:?

Question

a) 1.58
b) 0.79
c) 0.60
d) 0.40

Sorry my bad, the actual question is:
A chemical engineer submerges a 30 g mass in an unknown liquid, giving it an apparent mass of 20 g. The specific gravity of the object is 2.37. The specific gravity of the unknown liquid must therefore be:
a) 1.58
b) 0.79
c) 0.60
d) 0.40

Answer 1

You have VERY poorly worded the question, not to mention omitted necessary information needed (for us) to solve it (for you, since you cant do your own homework).

We need to know the volume of the mass, which can be obtained by knowing its density.

Also, the "mass" will not change mass when submerged in water, its weight will change, but its mass is always constant.
You are not looking for the liquid's "gravity", you are looking for its "specific gravity" or density.

You must have copied this question incorrectly, I cannot imagine a text book would be so terribly lax in their phrasing.


EDIT:

Now it is solvable.

Without going into a lot the detailed mathematical explanation.....

To put it simply, what happens when the object is submerged is that 10 gram's worth of the objects weight "disappears", this is caused by the mass of the liquid being displaced.

The volume of the object (30 grams with a density of 2.37 g/mL) is 12.66 mL. The object obviously displaced 10 grams worth of liquid when fully submerged, the liquid displaced has a volume equal to that of the object being submerged.
Density = mass / volume

Density of liquid = 10 grams / 12.66 mL
Density = .79 g/mL....which is choice b).

See how important it is to copy the question correctly.

Answer 2

You need to know the volume of the 30g mass or the volume increase in the liquid when the mass is entered, or you need to know the density of the mass.

Insufficient information.

Answer 3

I am going to take a wild guess since I have a 25% chance of gettting it right. I choose C). .60