Vsepr theory predicts linear geometry of electron groups have what angle around a central atom?

180°

Explanation:

According to VSEPR theory, if the valence shell of the ceteral atom in a molecule contains only two valence electron pairs, the valence electron pairs will arrange themselves along a straight line, forming a bond angle of 180°

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