JAMB Chemistry Past Questions & Answers - Page 63

From the dilution law

  C\(_1\)V\(_1\) = C\(_2\)V\(_2\)

  C\(_1\) = Initial Concentration of NaOH = 0.6M

  V\(_1\) = Initial Volume of NaOH = 300cm3

  C\(_2\) = Final Concentration of NaOH = 0.4M

  V\(_2\) = Final Volume of NaOH = ?

  V\(_2\) = \(\frac{C_1V_1}{C_2}\)

  V\(_2\) = \(\frac{0.6 \times 300}{0.4}\)

  V\(_2\) = 450 cm\(^3\)

Correct Computation as it follows the equation specified

When we burn coal on a fire, the bonds break apart and the energy is released in the form of heat. Coal contains about half as much energy per kilogram as cleaner fossil fuels such as gasoline, diesel, and kerosene—and that's one reason why steam engines have to burn so much of it.

Coal is the fuel used to power steam engines.

A catalyst is a substance that enables a chemical reaction to proceed at a usually faster rate or under different conditions (as at a lower temperature) than otherwise possible.

Oxygen is collected in downward displacement of water because:-

1. Oxygen is only slightly soluble in water. Therefore, it can be collected over water without the fear of excessive dilution.
2. Oxygen is slightly heavier than air, so it cannot be collected over air.

The quick-lime is a drying agent that can dry most gases except ammonia. Hence it removes the water vapour. Quick-lime which is calcium oxide reacts with the carbon dioxide forming calcium carbonate. Hence carbon dioxide and monoxide is eliminated leaving nitrogen, and the rare gases