Answer is: D) Light is emitted from an atom as an electron falls from an excited state to the ground state releasing a photon.
Electrons can jump from one energy level to another, absorbing or emitting electromagnetic radiation with a frequency ν (energy difference of the levels).
When electron jump from higher to lower energy level (shell), it emitting (releasing) energy.
For example, when the electron changes from n=4 (fouth shell) to n=2 (second shell), the photons are emitted.
Albert Einstein (1879-1955) proposed that a beam of light is a collection of discrete wave packets (photons) with energy hν, where h is Planck constant and ν is frequency.
The photons have a characteristic energy proportional to the frequency of the light.
Minimum frequency or the threshold frequency is energy below which no photoelectrons are emitted.
Above the minimum frequency, energy depends on the frequency of the light, not on the intensity of the light.
A Brønsted-Lowry acid is defined as a compound that gives hydronium ions to another compound—for example, hydrochloric acid gives H+ ions to compounds it reacts with. Brønsted-Lowry bases are compounds that can accept hydronium ions—when ammonia gets a hydronium ion from HCl, it forms the ammonium ion.
If two different elements combine separately with a fixed mass of a third element, the ratio of the masses in which they do so are either the same as or a simple multiple of the ratio of the masses in which they combine with each other.
