Answer:
The amount/type of stain
Explanation:
You would want to ensure that the stain was the same in both samples.
Answer:
A. Water
Explanation:
H2O means that there are two hydrogen and one oxygen in every water molecule.
Answer:

Explanation:
You look at the type of atom and their electronegativity difference.
If ΔEN <1.6, covalent; if ΔEN >1.6, ionic
Ar/Xe: Noble gases; no reaction
F/Cs: Non-metal + metal; ΔEN = |3.98 – 0.79| = 3.19; Ionic
N/Br: Two nonmetals; ΔEN = |3.04 - 2.98| = 0.
False, kinetic energy depends on an objects mass and speed