CM8001

a. Exothermic. Heat is released during the burning process.

b. Endothermic. Energy is absorbed by water to change from liquid to vapour phase.

c. Endothermic. Energy is absorbed by ice to change from solid to liquid phase.

For exothermic reactions, the energy absorbed during bond breaking is less than the energy released during bond formation.
Therefore, the bond strength of reactants is much less than the bond strength of products, causing large amounts of energy to be released during explosion.
Gases have a larger volume per mole than solids, thus, the reactants should be in solid state while reactants should be in gaseous state, such that there will be rapid expansion in terms of volume, causing a good explosion.

Temperature is a scale to measure heat energy.
Heat is the vibration of atoms while temperature is the measure of energy.
For example, temperature is the degree of hotness of a cup of coffee while the heat we feel is the transfer of heat energy from the coffee to our hands.

a. The gasoline has the same anti-knocking characteristics as a mixture of 98% iso-octane and 2% heptane.

b. Undetermined. Oxygenates are additives that increase the octane rating. Average fuel containing oxygenates have octane rating of 92 and since 98 is greater than 92, it is highly probable that the fuel contains oxygenates. However, this is not definite.