Answer:
The mass number is defined as the total number of protons and neutrons in an atom. The number of neutrons = mass number − atomic number.
Answer:
she can use crystalization method.
Explanation:
She should boil that liquid on flame and then cool it down on mederate temprature and check it out rather the crystals formed or not . if crystals are formed then there will be salts.
And if she want topredict the certain salt then she has to perform certain reactions.
Answer:
is the isotopic notation of the atom
Explanation:
The isotope notation is:

<em>Where a is the mass number = Number of protons + Number of neutrons</em>
<em>b is atomic number = Number of protons</em>
The atomic number define the nature of the atom, the element with atomic number = 15 is phosphorus, P:

a = 15 protons + 16 neutrons = 31
b = 15
is the isotopic notation of the atom.