What elements does the sun use in its fusion reaction? ?

How do you know when a chemical reaction has occurred

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.

Measurements that have similar values are: a. usually accurate b. sometimes accurate c. always accurate d. never accurate