Because room temperature is below the ignition temperature of petrol. At this temperature energy in the form of heat, flame, or electric spark is needed to start the reaction.
Answer:
Explanation:
A new Material is formed.
Basically, Chemical changes differ from Physical changes because in chemical changes, Substances have the ability to become a different substance.
Example:
Water to ice is a physical change because it is still water despite being a solid from liquid.
A Magnesium strip placed in CuSO4 solution made the Mg strip turn into a new substance which is MgSO4. this is a Chemical change because Mg has now become a different substance called MgSO4.
when sodium metal is dropped in water, hydrogen gas in liberated due to extreme heat released as the reaction is exothermic, gas catches fire.
The first and Third graph
