CM8001

A) exothermic, heat is being released when charcoal briquette burns.
B) endothermic, heat is absorbed to change water from liquid to gaseous state.
C) endothermic, heat is absorbed to change water from solid to liquid state.

In an exothermic reaction, delta H is negative. The sum of the relative bond strength of products is more than the sum of the relative bond strength of the reactants.
Chemical explosion occurs when a solid reactant forms a gaseous product. Therefore bond strength of reactant is very Low and that of the product is very high.

Heat is the energy that flows from a hotter object to a cooler object while temperature is a measure of the average speed of the heat flow from a hotter to a cooler object.
Example for heat: when you touch a hot pan, heat is felt by your hand which is cooler
Temperature: comparing a pan of 50 degrees celcius and 30, you will feel th heat of the 50 degrees C faster than that of 30 degrees C

A) it has a knocking characteristic of 98% isooctance and 2% heptane.

B) it is not possible to tell from the octane rating