The solubility of lead nitrate at 100°C is 140.0 g/100 g water. A solution at 100°C consists of 62.0 g of lead nitrate in 74.0 g of water. When the solution is cooled to 10°C, 25.0 g of lead nitrate crystallize out. What is the solubility of lead nitrate in g/100 g water at 10°C?

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

answer:

the reaction is type of combination reaction.

explanation:

on the product side, there are 2 molecules of bonded to fe   which means one atom of fe are combined two molecules of . so, balanced chemical equation becomes :

this reaction follows the reaction type of combination reaction. a combination reaction is defined as chemical reaction in which reactants combines together to form a single product.

1 is the answer to this problem