Answer is D 2 elements and a total of 3 atoms
Answer:
Exothermic reaction for the HCl, endothermic reaction for the water

Explanation:
Heat was lost by HCl as its temperature lowered, so it was an exothermic reaction for the HCL.
Heat was gained by water as its temperature increased, so it was an endothermic reaction for the water.
m = Mass of water = 100 g
c = Specific heat of water = 
= Change in temperature of water = 
Heat is given by

Heat gained by water is
.
Answer: A. True
Explanation: Combustion is a chemical process in which a substance reacts rapidly with oxygen and gives off heat. The original substance is called the fuel, and the source of oxygen is called the oxidizer. ... During combustion, new chemical substances are created from the fuel and the oxidizer.
Answer:
Physical Properties
Explanation:
You are able to see physical properties but are unable to see chemical properties.