Answer:
Exothermic.
Explanation:
Exothermic is when he leaves the system. A way to remember is the "ex" which is a prefix/root/suffix or something that pretty much means leaving, I think. For example how it's in "Exodus" and "Exit", I think.
Endothermic is when it goes into the system. Similar to "ex" but with inside, I think. For example how it's in "Endoskeleton", I suppose.
Answer: 
Explanation:- Volume percentage is the ratio of volume of solute to the volume of solution defined in terms of percentage.

Given: volume of solute = 29.4 ml
Volume of solution= 359 ml

Answer:
sulfur promotes oxide-reduction reactions.
Explanation:
In stagnant water, some solutes tend to precipitate. When Sulfur precipitate and touch a metal, Sulfur is being reduced and the metal is oxidated. This depends of potential redox of each element.
Answer:
A planet's orbital speed changes, depending on how far it is from the Sun. The closer a planet is to the Sun, the stronger the Sun's gravitational pull on it, and the faster the planet moves. The farther it is from the Sun, the weaker the Sun's gravitational pull, and the slower it moves in its orbit.