A solution containing mg2 was buffered to ph 10 and titrated with edta. Eriochrome black t, with p������a values of 6. 3 ( p������a2 ) and 11. 6 ( p������a3 ), was used as the indicator.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

it should have an internal chamber and two thermometers sticking out of the top. the internal chamber will also be closed off from the outside.