Explanation:
On dissolution of chromium(II) sulfate is water 2 ions of chromium(III) ion and and 3 sulfate ions are formed.
The balanced chemical equations of the dissolution of chromium (II) sulfate:

On dissolution of gold(III)nitrate is water 1 ions of gold(III) ions and and 3 ions of nitrate ions are formed.
The balanced chemical equations of the dissolution of gold(III) nitrate:

Density = mass / Volume 0.856 g/cm3 = x / 30 cm3(0.856)(30) = xx = 25.68 grams
Answer:
An endothermic reaction
Explanation:
A positive sign indicates that energy is absorbed. Hence it is an endothermic reaction.
A reversible reaction is indicated by a double arrow on the chemical equation.
A spontaneous is indicated by negative Gibbs Free Energy (G) value.
An exothermic reaction is indicated by a negative enthalpy change