7. A student dissolved Sg of table salt in 100 mL of water in a beaker. Compared to the total mass of the salt and water before mixing, which is true?
a) The total mass of the solution will increase by a small amount
b) The total mass of the solution will increase by a large amount
c) The total mass of the solution will decrease by a snall amount
d) The total mass of the solution will neither increase nor decrease

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.