d and f BLOCK ELEMENTS

Why are alloys often harder than their constituent pure metals?

• They have fewer atoms
• They are always ionic
• The presence of different sized atoms disrupts crystal planes and impedes dislocation movement
• They have lower melting points

In the context of alloy formation, what does the term 'blend' imply according to the text?

• A chemical compound
• A pure element
• A mixture of metals
• An ionic compound

What is the primary reason for the chemical inertness of interstitial compounds like TiC?

• They are noble metals
• They lack reactive electrons
• They are purely ionic
• The strong metal-carbon bonds and stable lattice structure

Which of the following is NOT listed as a use for transition metals or their compounds in catalysis in the provided text?

• Oxidation of sulfur dioxide in the Contact Process
• Hydrogenation of alkenes
• Production of ammonia via the Haber-Bosch process
• Oxidation of iodide ions by persulfate ions

What does the term 'non-stoichiometric' imply about the composition of a compound?

• The ratio is always a simple whole number
• The compound is always ionic
• The ratio of elements is not fixed and can vary within a range
• The compound has a fixed molecular weight