Answer:
1. Two to decompose
Explanation:
It's going to be a decomposition so you can eliminate answers 3 and 4. It is a decomposition because it is splitting apart. Then you can figure out that it is going to be two instead of four by balancing the equation
H2O2 → 2H2O + O2

Answer:
2)The particles in a liquid are moving past one another constantly.
3)The particles in gas move freely in all directions.
4)The particles in a solid vibrate in a fixed position.
6)The particles in a gas have few attractions between them.
7)The particles in all states of matter are always moving.
Explanation:
Answer:

Explanation:
The atomic number (Z) of copper is 29 and this isotope has an atomic mass (A) of 70.
The general symbol for an isotope E is
.
The atomic number is a left subscript, and the atomic mass is a left superscript.
