What does the symbol (–hfus) indicate in a phase change?

(D) Liquid is being formed.

Explanation:

The enthalpy of fusion of a substance (–Hfus) is the change in its enthalpy when the substance changes its state from a solid to a liquid. It happens when heat is supplied to some quantity of substance which is originally in solid state & it turns into liquid.

Example- melting of ice.

To melt ice energy is required. Approximately, 333 kJ of energy is needed to heat 1 kg ice to convert into liquid.

a is the answer to this question

explanation:

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.