A pH of 7 or lower makes something an acid so it would be 3
The emission spectrum of an atom consists of limited lines that are unique to a given element.
According to the Bohr model of the atom, energy is absorbed or emitted when an atom moves from one energy level to another. Since energy is quantized, the spectrum of atoms often consists of single lines.
Hence, the true statement about atomic spectrum is that; "the light that an element emits is made up of a limited number of narrow lines that produce a unique pattern or atomic emissions spectrum for that element."
Learn more about atomic spectrum: brainly.com/question/2049494
A solution may exist in any phase so your answer is D. any of the above
hope this helps :)
Answer:
A. X is an element or a compound while Y is a mixture
