Q. Why does boron triflouride behave as a Lewis acid ?

Q. Rationalise the given statements and give chemical reactions.
(a) Lead(II) chloride reacts with $C{l}_2$ to give $PbC{l}_4$.
(b) Lead(IV) chloride is highly unstable towards heat.
(c) Lead is known not to form an iodide, $Pb{I}_4$.

Q. How can you explain higher stability of $BC{l}_3$ as compared to $TlC{l}_3$?

Q. Describe the shapes of $B{F}_3$ and $B{H}_4^{-}$. Assign the hybridisation of boron in these species.

Q. What is the state of hybridisation of carbon in (a) $C{O}_3^{-2}$ (b) diamond (c) graphite?

Q. Consider the compounds $BC{l}_3$ and $CC{l}_4$. How will they behave with water? Justify.

Q. Aluminium trifluoride is insoluble in anhydrous HF but dissolves on addition of NaF. Aluminium trifluoride precipitates out of the resulting solution when gaseous $B{F}_3$ is bubbled through. Give reasons.

Q. Suggest reasons why the $BF$ bond lengths in $B{F}_3$ (130 pm) and ${B{F}_4}^{-}$ (143 pm) differ.

Q. Explain what happens when boric acid is heated.

Q. Write reactions to justify amphoteric nature of aluminium.

Q. Discuss the pattern of variation in the oxidation states of (i) $B$ to $Ti$ and (ii) $C$ to $Pb$.

Q. Suggest a reason as to why $CO$ is poisonous.

Q. Explain structures of diborane and boric acid.

Q. What are electron deficient compounds ? Are $BC{l}_3$ and $SiC{l}_4$ electron deficient species? Explain.

Q. What happens when,

Q. Write the resonance structures of $C{O}_3^{-2}$ and ${HC{O}_3}^{-}$.

Q. How is excessive content of $C{O}_2$ responsible for global warming ?

Q. Explain the difference in properties of diamond and graphite on the basis of their structures.

Q. Is boric acid a protic acid? Explain.

Q. If BCl bond has a dipole moment, explain why $BC{l}_3$ molecule has zero dipole moment.