Based on MO theory, which of the following molecules and ions have the largest bondorder?A. H2 B. H2+C. He2 D. He2+

To answer this question, we need to understand the Molecular Orbital (MO) Theory. According to MO Theory, bond order is calculated as the difference between the number of bonding electrons and the number of antibonding electrons, divided by 2.

Let's calculate the bond order for each molecule/ion:

A. H2: There are two bonding electrons (from the two hydrogen atoms) and no antibonding electrons. So, the bond order is (2-0)/2 = 1.

B. H2+: This ion has one electron removed, so there is one bonding electron and no antibonding electrons. The bond order is (1-0)/2 = 0.5.

C. He2: Each helium atom contributes 2 electrons, for a total of 4. However, helium is a noble gas and its electrons fill both the bonding and antibonding orbitals. So, the bond order is (2-2)/2 = 0.

D. He2+: This ion has one electron removed, so there are 3 electrons. Two fill the bonding orbital and one fills the antibonding orbital. The bond order is (2-1)/2 = 0.5.

So, based on these calculations, H2 (A) has the largest bond order.