There are two bits of information here. First, you know the material weighed 15 grams. Second, you know it increased in volume. You must address both of those.
In the answers, both a and c deal with mass. a says it weighs more; c says it weighs the same. Do you think freezing anything causes the mass of it to change. Of course not. So c must be correct.
Both b and d deal with density. b says it increases; d says it stays the same. You know density = mass/volume. You know mass is 15 grams and it doesn't change. The statement in the problem says volume increases. So if the denominator of d = m/v gets larger what happens to the density. It gets smaller. So neither b nor d are correct. The only correct answer there is c. Do you have trouble seeing that the mass doesn't change. Suppose we have a piece of paper that has a mass of 15 g and cut it into two pieces. Guess what. The two pieces still have a mass of 15 g. What if we put it in the freezer at -20. It still has a mass of 15 g. What if we burn the two pieces of paper. Burning the paper converts it into CO2(a gas), water (a gas at burning temperatures), and leaves charred paper pieces. If we collect the charred paper remnants, and the water, and the CO2 gas all of that will weigh 15 g. Hope this helps.
Fifteen grams of a liquid plastic are frozen in a physical change that increases the volume. What can be known about the plastic after the change?
A) It will weigh more than 15 grams.
B) It will have an increased density.
C) It will still weigh 15 grams.
D) It will still have the same density.
I'd like an explanation rather than an answer, if possible. I just don't understand this question.
1 answer
1 answer