D will because water just turns from liquid to a gas by adding heat. That is a physical change. The other equations are chemical changes.
<u>Answer:</u> The partial pressure of oxygen is 160 mmHg
<u>Explanation:</u>
We are given:
Percent of oxygen in air = 21 %
Mole fraction of oxygen in air = 
To calculate the partial pressure of oxygen, we use the equation given by Raoult's law, which is:

where,
= partial pressure of oxygen = ?
= total pressure of air = 760 mmHg
= mole fraction of oxygen = 0.21
Putting values in above equation, we get:

Hence, the partial pressure of oxygen is 160 mmHg
Answer:
the heat is circulating in the same spot rather than airing out into the open
Explanation:
It's B - convection that is correct...
Here are my reasonable beliefs
For number 1. what the answer seems to be is C.Than looking are numbers two and three their answers are both B
My reasoning for them is , because if you think about the solid liquid gas's this is a common result in most experiments.also for number two , you have to decrease ( go down ) on the concentration ( hardness ) of the subject to get a more powerful solution
So far as number one , for it to be water the atoms have to be far away from the other moving freely , to be a solid they can barely move at all.