Difference between rapid combustion and spontaneous combustion.

The difference between rapid combustion and spontaneous combustion...

Explanation:

Rapid combustion is a form of combustion, otherwise known as a fire, in which large amounts of heat and light energy are released, which often results in a flame.Whereas spontaneous combustion is the ignition of organic matter (e.g. hay or coal) without apparent cause, typically through heat generated internally by rapid oxidation.

d: the voltage of the secondary coil is less than that of the primary coil.

im not suree sorry if wrong

indicate valleys, hills, steepness and gentleness of slopes.

explanation:

contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.