According to molecular orbital theory, which of the following ions are paramagnetic?   I. H2−   II. Be2+   III. O22−

Between Li, Na, K, Rb, and Cs, which would be the most reactive in water and why?

Consider the following molecule. How many sigma bonds does it contain?

Among the following molecules, which should have at least one resonance structure?      SO2, SO3, SO32−

Use the bond enthalpies in the table below to determine the enthalpy change for the following unbalanced reaction: N2O(g) + H2O(g) + O2(g) → HNO3(g) Substance ΔH°f (kJ mol−1) N2O(g) +81.6 H2O(g) −241.82 O2(g) 0 HNO3(g) −133.9

In the hydrazine molecule, HNNH, what type of bond(s) exist between the two N atoms? (Hint: work out the Lewis structure)

Which of the following ions has a ground-state electron configuration of 1s22s22p6?   I. Ne+   II. O2−   III. Na+

Which of the following molecules contains a single covalent bond?

How many polar bonds does CHCl3 contain?

Use the bond enthalpies in the table below to determine the enthalpy change for the following unbalanced reaction: B2H6(g) + F2(g) → BF3(g) + HF(g)  Substance ΔH°f (kJ mol−1) B2H6(g) +36.4 F2(g) 0 BF3(g) −1136.0 HF(g) −273.3