How do I do this? Please help asap.

How could a student test the effect of removing heat from a gas that is stored in a sealed container? what must occur in order for matter to change states?

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.

In a reduction half-reaction, which amount is shown