If an electron moves up from the first orbit to the higher energy levels, energy will be absorbed by the electron itself and no emission line produced.
But if it moves from the orbits 6,5,4 and 3 to orbit 2, energy will be released by the electron and different emission lines wll be produced.
Liquid petrol does not ignite spontaneously when exposed to the air because there is not enough molecules that contains energy to reach the activation energy. As a result, the reaction cannot proceed and a supply of energy should be added for the reaction to occur.
Our solar system formed about 4.5 billion years ago from a dense cloud of interstellar gas and dust. The cloud collapsed most likely due to a shockwave form a nearby exploding start called a supernova
Answer:
A calculator has an endifiite shape because all of its atoms are touching each other
