Which of the following enthalpy may be positive or negative?

Which of the following enthalpy is always positive ?

Which of the following enthalpies is always negative ?

Which of the following elements has the most negative electron gain enthalpy?

Which of the following has the highest positive electron gain enthalpy ?

Which of the following has the highest positive electron gain enthalpy ?

Which of the following will have the most negative electron gain enthalpy and which the least negative? O, S, F and CI . Explain.