99
Mo
42
→
99
Tc
43
+ X
a) Identify X.
How do I figure this out?

The density would be 1.622

Show and image of the mixtures or write them

Answerδh > 0explanationc₆h₆  (s)  → c₆h₆ (l)if you are changing it from a solid to a liquid, you are pretty much melting the solid. this requires heat energy. therefore, the reaction is endothermic (takes in energy); the system enthalpy increases as the reaction proceeds: δh > 0.

Ibelieve the answer is weathering,hope my answer has you : )