What is the molarity of an NaOH solution if 20. milliliters of 2.0 M HCl is required to exactly neutralize 10. milliliters of the NaOH solution? 1.
1.0 M
2.
2.0 M
3.
0.50 M
4
4.0 M

nacl is added to the aqueous of what? ? in order to get a proper answer you have to specify the exact composition of the aqueous solution.

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.