3. Define isobar 75 points

1.

meteorology A line drawn on a map or chart connecting places of equal or constant pressure.

2.

nuclear physics Either of two nuclides of different elements having the same mass number.

3.

thermodynamics A set of points or conditions at constant pressure.

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

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