Answer:
chemical
Explanation:
It is breaking down the molecules. That's chemistry
NO₂ is a brown gas while N₂O₄ is colorless. If heating causes a brown color to persist, then this means that heating causes the reaction to shift backwards and produce NO₂. Therefore, the reaction must be exothermic.
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.
Work = force*distance
Work = 670 * 5
Work = 3350 Nm
True but in more depth they both have the some same qualities in function but provide for each other when one makes oxygen, H2O, and energy and cellular respiration makes CO2 and glucose