a. Exothermic. We are able to feel the heat radiating from the charcoal.
b. Endothermic. Evaporation is an endothermic process heat is taken away.
c. Endothermic. Heat energy is absorbed to melt the ice. Hydrogen bonds are broken and water molecules are allowed to move about freely.

Bond strength of the reactants has to be weaker and easy to break while bond strength of products needs to be stronger. Volume changes rapidly as gases are produced.

Heat is the flow of energy from hotter to less hot body while temperature is the measure of average speed of heat.

E.g. Energy from hot milo is transferred to colder ice cubes. Temperature will be between initial temperature of ice and milo.

a. 98% of iso-octane and 2% heptane.
b. No. Octane rating only gives information about knocking characteristics.