JAMB Chemistry Past Questions & Answers - Page 66

Diamond is a covalent macromolecule, and typical of a covalent substance is an insulator. All valence electrons are localized in well-defined covalent bonds and hence are not free to move through the structure

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

2NaOH + H\(_2\) SO\(_4\)↔Na\(_2\)SO\(_4\) + 2H\(_2\)O

  V x 0.5M = 2(10 x 1.25)

  0.5V = 2 x 12.5

  0.5V = 25

  V = 250.5 = 50cm\(^2\)

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.