The metal extracted from cassiterite is

A. calcium

B. copper

C. tin

D. sodium

E. lead

In which of the following is the oxidation number of nitrogen zero?

A. SO₂ and NH₃

B. NaNO₃

C. HNO₂

D. NOI₃

E. N₂

The separation of a mixture of calcium trioxocarbonate (lV) and sodium trioxocarbonate (IV) is most easily carried out by using the differences in their

A. physical states

B. melting points

C. values

D. solubility

E. boiling points

When air is passed through a heated tube containing finely divided copper, the component that is absorbed in the process is

A. carbon (IV) oxide

B. nitrogen

C. oxygen

D. water vapour

E. noble gases

What is the amount (in mole) of sodium trioxocarbonate (IV) in 5.3 g of the compound? (Na₂CO₃ = 106)

A. 0.05

B. 0.10

C. 0.20

D. 0.50

E. 2.00

Which of the processes represented by the following equations has the greatest positive entropy change?

A. C₆H_3(l) → C₆H _{6 (g)}

B. H₂O _(s) → H₂O_(l)

C. CuO_(s) + H_2(g) → Cu_(s) + H₂

D. Na₂CO_3(s) + nH₂O_(l) →Na ₂CO₃nH₂O_(s)

E. S_(s) → S_(l)

Which of the following elements can from more than one acidic oxide?

A. Hydrogen

B. Sulphur

C. Carbon

D. Alumium

E. Iron