Chemistry Past Questions and Answers

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 Rf. values
D Solubility
E Boiling points

Question 152:

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

Question 153:

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

Question 154:

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

A C₆H₃_(l) â†’ C₆H ₆_(g)
B H₂O _(s) → H₂O_(l)
C CuO_(s) + H₂_(g) â†’ Cu_(s) + H₂
D Na₂CO₃_(s) + nH₂O_(l) â†’Na ₂CO₃nH₂O_(s)
E S_(s) â†’ S_(l)

Question 155:

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

A Hydrogen
B Sulphur
C Carbon
D Alumium
E Iron