Which 4 diagrams are stable and which 4 are unstable?

What is the nature of the ca-cl bond in a molecule of calcium chloride (cacl2) if the electronegativity value of calcium is 1.0 and that of chlorine is 3.16?

What is the mass defect of a mole of nuclei with 1.8 x 10^15 j/mol binding energy?

The boiling point of propanoic acid is higher than that of 1-butanol because: propanoic acid has a higher molecular weight than 1-butanol. propanoic acid is more soluble in water than 1-butanol. propanoic acid is a better hydrogen bond donor than 1-butanol. propanoic acid forms hydrogen bonded dimers and 1-butanol does not. 1-butanol forms hydrogen bonded dimers and propanoic acid does not.