Problem 12
Explain the difference in properties of diamond and graphite on the basis of their structures.
Problem 13
Rationalise the given statements and give chemical reactions: \- Lead(II) chloride reacts with \(\mathrm{Cl}_{2}\) to give \(\mathrm{PbCl}_{4}\). \- Lead(IV) chloride is highly unstable towards heat. \- Lead is known not to form an iodide, \(\mathrm{PbI}_{4}\).
Problem 15
If B-Cl bond has a dipole moment, explain why \(\mathrm{BCl}_{3}\) molecule has zero dipole moment.
Problem 16
Aluminium trifluoride is insoluble in anhydrous HF but dissolves on addition of NaF. Aluminium trifluoride precipitates out of the resulting solution when gaseous \(\mathrm{BF}_{3}\) is bubbled through. Give reasons.
Problem 17
Suggest a reason as to why \(\mathrm{CO}\) is poisonous.
Problem 18
How is excessive content of \(\mathrm{CO}_{2}\) responsible for global warming?
Problem 19
Explain structures of diborane and boric acid.
Problem 20
What happens when (a) Borax is heated strongly, (b) Boric acid is added to water, (c) Aluminium is treated with dilute NaOH, (d) \(\mathrm{BF}_{3}\) is reacted with ammonia?
Problem 21
Explain the following reactions (a) Silicon is heated with methyl chloride at high temperature in the presence of copper; (b) Silicon dioxide is treated with hydrogen fluoride; (c) \(\mathrm{CO}\) is heated with \(\mathrm{ZnO}\); (d) Hydrated alumina is treated with aqueous NaOH solution.
Problem 22
Give reasons : (i) Conc. HNO \(_{3}\) can be transported in aluminium container. (ii) A mixture of dilute \(\mathrm{NaOH}\) and aluminium pieces is used to open drain. (iii) Graphite is used as lubricant. (iv) Diamond is used as an abrasive. (v) Aluminium alloys are used to make aircraft body. (vi) Aluminium utensils should not be kept in water overnight. (vii) Aluminium wire is used to make transmission cables.
