Which of the following is/are correct?

Options

A. For `A(g) +e^(-) rarr A^(-) (g) DeltaH` may be negative
B. For `A^(-)(g) +e^(-) rarr A^(2-) (g) DeltaH` may be negative
C. For `A^(-)(g)+e^(-) rarr A^(2-)(g) DeltaH` must be positive
D. For `A^(+3) (g) +e^(-) rarr A^(+2)(g)DeltaH` must be negative

Answer

A, C, D