Asmall object, usually built to scale, that represents in detail another, often larger object.

Ithink the answer is a or d.

1) according to the law of conservation of mass ,in all chemical reactions total mass is unchanged

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.

Answerstrong acids and bases completely dissociate in water.this is how strong acids and bases are defined. they will ionize 100% in solution, making a non-reversible reaction