Question

The oxidation number of As is:
A. $+ 2\,and\, + 3$
B. $+ 3\,and\, + 5$
C. $+ 3\,and\, + 4$
D.None of these

Answer 1

Hint : Arsenic is a chemical element with the atomic number $33$ and the symbol As. Many minerals contain arsenic, which is normally found in conjunction with sulphur and metals, but it can also be found as a pure elemental crystal. Arsenic is classified as a metalloid.

Complete Step By Step Answer:
Since arsenic [As] belongs to the periodic table's group $15$ , it can have both $+ 3\,and\, + 5$ oxidation states.
Actually, it is known that, in simple terms, the oxidation number is the number assigned to the elements in a chemical mixture. The oxidation number is defined as the total number of electrons that atoms in a molecule can share, lose, or gain when forming chemical bonds with atoms of another substance.
We can clearly say that the oxidation state is also known as the oxidation number. However, depending on whether we are discussing the electronegativity of the atoms or not, these concepts may have a different definition. In coordination chemistry, the term oxidation number is commonly used.
In general, the oxidation state or number aids in the description of electron transfer. However, students should be aware that this is not the same as a formal charge, which defines atom arrangement. In redox reactions, the oxidation number/state is often used to assess the changes that occur. In the meantime, it's very close to valence electrons.
More electronegative atoms in molecules receive electrons from a less electronegative atom, resulting in negative oxidation states. The number of electrons lost or gained equals the oxidation state's numerical value.
The oxidation state or number of an atom or ion in a molecule/ion is determined by:
i) Calculating the constant oxidation state of other atoms/molecules/ions bonded to it, and
ii) Adding the total charge of a molecule or ion to the total oxidation state of the molecule or ion.
So the Option B is the correct answer.

Note :
An atom in a substance is given an oxidation number, which is a number. The oxidation number shows whether electrons are lost or gained and may be positive, negative, or zero. To put it another way, the oxidation number is a number that aids in the tracking of electrons in an atom.