Question

1.Although metals form basic oxides, which of the following metals form an amphoteric oxide?

(a) Na

(b) Ca

(c) Al

(d) Cu


2. Generally, non-metals are not conductors of electricity. Which of the following is a good conductor of electricity?

(a) Diamond

(b) Graphite

(c) Sulphur

(d) Fullerene

Answer 1

1. Although metals form basic oxides, Aluminium forms an amphoteric oxide

Hence, correct answer is option (c) Al

• An amphoteric oxide is one which shows both acidic and basic properties.
• Here , Al forms amphoteric oxides because it reacts with acids as well as bases to give salt and water .
• The main reason behind is that the electronegativity difference between Al and O is really small .
• Reaction with acid :- Al2O3 + 6HCl → 2AlCl3 + 3H2O ( This shows basic nature )
• Reaction with base :- Al2O3 + 2NaOH → 2NaAlO2 + H2O ( This shows acidic nature )

2. Generally, non-metals are not conductors of electricity but Graphite is good conductor of electricity .

Hence, correct answer is option (b) Graphite

• Graphite has delocalised electrons just like metals .
• The electrons are free to move between the layers so, it can conduct electricity .