<u>Answer:</u>
<u>For 1:</u> The correct answer is Option A.
<u>For 2:</u> The correct answer is Option B.
<u>For 3:</u> The correct answer is Option C.
<u>Explanation:</u>
<u>For 1:</u>
Atomic number is defined as the number of electrons or number of protons that are present in a neutral atom. It is represented as Z.
Z = Atomic number = Number of electrons = Number of protons
Mass number is defined as the sum of number of protons and number of neutrons present in an atom. It is represented as A.
A = Mass number = Number of protons + Number of neutrons
Hence, the correct answer is Option A.
- <u>For 2:</u>
The isotopic representation of an atom is:
where,
Z = Atomic number of the atom
A = Mass number of the atom
X = Symbol of the atom
We are given:
An isotopic representation of beryllium atom:
Thus, the number '4' represents the atomic number of beryllium, number '9' represents the mass number of beryllium atom.
Hence, the correct answer is Option B.
- <u>For 3:</u>
In CO compound:
Mass of oxygen = 16 g
Mass of carbon = 12 g
In compound:
Mass of oxygen = 32 g
Mass of carbon = 12 g
Thus, the ratio of mass of oxygen in and CO is:
Hence, the correct answer is Option C.