Which of the following statements about buffers is true? Group of answer choices A buffer composed of a weak acid of pKa = 5 is stronger at pH 4 than at pH 6. At pH values lower than the pKa, the salt concentration is higher than that of the acid. The strongest buffers are those composed of strong acids and strong bases. The pH of a buffered solution remains constant (exactly the same) no matter how much acid or base is added to the solution. When pH = pKa, the weak acid and salt concentrations in a buffer are equal.

When pH = pKa, the weak acid and salt concentrations in a buffer are equal.

Explanation:

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.