For a $\mathrm{H}_{2}$ molecule, the ground state wave function is $\psi_{1,2}=\phi_{1,2}\,\sigma(1,2)$ where $\phi$ refers to the space part and $\sigma$ to the spin part. Given that $\phi_{1,2}=\phi_{2,1}$ the form of $\sigma(1,2)$ would be
(a)$\alpha(1) \beta(2)$
(b)$\alpha(2) \beta(1)$
(c)$\alpha_1\beta_2-\alpha(2)\beta(1)$
(d)$\alpha_1\beta_2+\alpha(2)\beta(1)$
Answer
Answer: C ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
A symmetric spatial part must be paired with an antisymmetric spin part: α(1)β(2) − β(1)α(2) (the singlet).