Which bonds cause the boiling point of water to be significantly greater than that of hydrogen sulfide?

A.     London (dispersion)

B.     Covalent

C.     Ionic

D.     Hydrogen

The graph shows the boiling points of the hydrides of group 16 elements.

Explain the increase in the boiling point from H₂S to H₂Te.

What are the predicted electron domain geometries around the carbon and both nitrogen atoms in urea, (NH₂)₂CO, applying VSEPR theory?

Compare, giving a reason, the length of the bond between the carbon atoms in ethyne with that in ethane, C₂H₆.

Determine the type of bond present in SbBr₃, showing your method. Use sections 8 and 29 of the data booklet.

Determine the percentage of ionic bonding in alumina using sections 8 and 29 of the data booklet.

Compare, giving a reason, the length of the bond between the carbon atoms in ethyne with that in ethane, C₂H₆.

Identify the type of bonding in sodium hydrogencarbonate.

Between sodium and hydrogencarbonate:

Between hydrogen and oxygen in hydrogencarbonate:

A chloride of titanium, TiCl₄, melts at 248 K. Suggest why the melting point is so much lower than that of KCl.

State and explain the difference in bond strength between the nitrogen atoms in a hydrazine and nitrogen molecule.

(i) Suggest why incomplete combustion of plastic, such as polyvinyl chloride, is common in industrial and house fires.

(ii) Phthalate plasticizers such as DEHP, shown below, are frequently used in polyvinyl chloride.

With reference to bonding, suggest a reason why many adults have measurable levels of phthalates in their bodies.

Identify the type of bonding in sodium hydrogencarbonate.

Between sodium and hydrogencarbonate:

Between hydrogen and oxygen in hydrogencarbonate:

Which compound contains both ionic and covalent bonds?

A.  $\text{MgO}$

B.  ${\text{CH}}_{\text{2}}{\text{Cl}}_{\text{2}}$

C.  ${\text{CH}}_{\text{3}}\text{COOH}$

D.  $\text{NaOH}$

Which compound has the shortest C to N bond?

A.  HCN

B.  CH₃CH₂NH₂

C.  CH₃CHNH

D.  (CH₃)₂NH

Which of these species contains the shortest carbon to oxygen bond length?

A.  ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{O}}^{-}$

B.  ${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{OH}$

C.  ${\mathrm{CH}}_3{\mathrm{COO}}^{-}$

D.  ${\mathrm{CH}}_3\mathrm{COOH}$

Outline two differences between the bonding of carbon atoms in C₆₀ and diamond.

Explain why C₆₀ and diamond sublime at different temperatures and pressures.

Explain why the hydrides of group 16 elements (H₂O, H₂S, H₂Se and H₂Te) are polar molecules.