Answer: negative , from , to , exothermic
Explanation:
An endothermic reaction is a type of chemical reaction in which energy is absorbed from the surrounding. The temperature of the surrounding decreases.
An Exothermic reaction is a type of chemical reaction in which energy is released into the surrounding. The temperature of the surrounding increases.
Endothermic reactions are those in which heat is absorbed by the system from the surroundings and exothermic reactions are those in which heat is released by the system to the surroundings. 
for Endothermic reaction is positive and
As on dissolution of salt, the temperature of water increases, the heat has been released from system into surroundings and thus is negative.
Answer:
A. R represents chemical energy; P represents thermal energy.
Step-by-step explanation:
The molecules in the gas contain chemical energy (R).
When the gas burns, the chemical energy is released as heat, or thermal energy (P).
It can be a compound or a single element. An element is a pure substance that cannot be separated into simpler substances by chemical or physical means. There are about 117 elements, but carbon, hydrogen, nitrogen and oxygen are only a few that make up the largest portion of Earth.
I would say pure substances
Answer:
No, gases move freely all over the place, liquids move more freely but in a more contained area, and solids the molecules are rigid, at the most the movement is small vibration as the molecules put pressure on one another to hold their form and stay in place.
Answer:
only one atom of that element
Explanation:
Example:
H2 O has two hydrogenatoms and ONE Oxygen atom
