Answer:

Explanation:
1. Calculate the moles of NaOH.
2. Calculate the volume of NaOH

Answer : Option C) The Octet Rule
Explanation : Atoms have a tendency to complete their outer energy level. This is known as Octet Rule.
The octet rule is a chemical rule of thumb which reflects the observation, that atoms of main-group elements tends to combine in such a way that each atom gets eight electrons in its valence shell, which gives it the same electron configuration as that of a noble gas.
In short, the tendency of an atom to fill its valence shell and attain a stable state it acquires or donates the electron is called as octet rule.
Since an acidic salt solution is produced when a strong acid neutralizes a weak base, the pH of the salt solution formed when HCl is added to R2NH will be less than 7.
<h3>What is a neutralization reaction?</h3>
A neutralization reaction is the react ion between an acid and a base to form salt and water only.
Neutralization reactions can either produce a neutral solution, an acidic solution or an alkaline solution at equivalence point.
When a strong acid is added to a weak base, the pH of the salt solution formed will be less than 7.
Therefore, the pH of the salt solution formed when HCl is added to R2NH will be less than 7.
Learn more about pH at: brainly.com/question/940314
Answer = B = Neutrons and Mass Number
Isotopes are defined as those atoms which have same atomic number but different atomic masses.
Atomic mass is basically the number of protons and neutrons present in an atom.
Atomic number is the number of protons present in an atom.
So, in isotopes the number of protons are same but the number of neutrons vary due to which atomic masses also vary.
In given three isotopes, all have same number of protons but different number of neutrons.
i.e.
H-1 = 1 P + 0 N = 1 u (Proton)
H-2 = 1 P + 1 N = 2 u (Deuterium)
H-3 = 1 P + 2 N = 3 u (Tritium)
Hence, it is clear that the number after H shows a change in number of neutrons and mass number.