Inorganic Chem MCQ question

Which of the following properties does not apply to modern ceramics?
		A.	High melting point
		B.	Application in engineering
		C.	Corrode readily
		D.	Very hard
Which of the following statements about aluminium is not true?
	A.		It is extracted by electrolysis.
	B.		Its chloride is covalent
	C.		It is soluble in concentrated nitric acid
	D.		It is soluble in sodium hydroxide solution

Explanation

With concentrated nitric acid, the aluminium metal is being oxidised causing the thickening of the aluminium oxide layer.

Which of the following statements is true of dimer Al2Cl6?
	A.		It is an ionic compound.
	B.		Aluminium atom undergoes sp2 hybridisation.
	C.		It is a white solid which melts when heated.
	D.		There are two coordinate covalent bonds in the molecule.
When sodium sulphide is added to an aqueous solution of aluminium chloride, the gas evolved is
		A.	Cl2
		B.	CO2
		C.	H2S
		D.	HCl
		Explanation 2[Al(H2O)6]3+ (aq) + 3S2- (aq) → 2Al(OH)3.3H2O (s) + 3H2S(g)

Why is the aqueous solution of an aluminium salt acidic?
	A.	[Al(H2O)6]3+ ion receives a proton in aqueous solution.
	B.	[Al(H2O)6]3+ ion donates a proton in aqueous solution.
	C.	[Al(H2O)6]3+ ion disproportionate and produces H+ (aq) ions.
	D.	Acidic [Al(H2O)6OH]2+ ions are produced in solution.
	Explanation In the the salt solutions the complex aluminium ion behave accordingly: [Al(H2O)6]3+ (aq) + H2O (l) ↔ [Al(H2O)5(OH)]2+ + H3O+ (aq)

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