Bright Line Emission Spectrum: As the excited electron returns to ground state (it's lower energy level) the energy it originally absorbed is released as discrete lines of light.
Answer:
well they form by heat and pressure
Empirical formula is the simplest ratio of components making up the compound. the molecular formula is the actual ratio of components making up the compound.
the empirical formula is CH₂. We can find the mass of CH₂ one empirical unit and have to then find the number of empirical units in the molecular formula.
Mass of one empirical unit - CH₂ - 12 g/mol x 1 + 1 g/mol x 2 = 12 = 14 g
Molar mass of the compound is - 252 .5 g/mol
number of empirical units = molar mass / mass of empirical unit
= 
= 18 units
Therefore molecular formula is - 18 times the empirical formula
molecular formula - CH₂ x 18 = C₁₈H₃₆
molecular formula is C₁₈H₃₆
Evaporation happens<span> when atoms or </span>molecules<span> escape from the liquid and turn into a vapor. Not all of the </span>molecules in a liquid have the same energy. <span>Sometimes a </span>liquid<span> can be sitting in one place (maybe a puddle) and its molecules will become a </span>gas<span>. That's the process called </span>evaporation<span>. It can happen when liquids are cold or when they are warm. It happens more often with warmer liquids. You probably remember that when matter has a higher temperature, the molecules have a higher </span>energy<span>. When the energy in specific molecules reaches a certain level, they can have a </span>phase change<span>. Evaporation is all about the energy in individual molecules, not about the average energy of a system. The average energy can be low and the evaporation still continues. </span>
