The valency of an oxygen atom is ______.

Q. The salt of an oxyacid of a metal $M$ contains one sulphur and four oxygen atoms. The valency of metal $M$ is:

Q. Statement-1: An atom having a valency of two can combine with two other atoms, each having a valency of one.

Statement-2: The valency of carbon in carbon dioxide $\left(C{O}_2\right)$ is two.

Q. The oxide of a metal contains 40% of oxygen. The valency of metal is 2. What is the atomic weight of the metal?

Q. The atomic number of an element which shows a valency of $+3$ is :

Q. An atom with 3 protons and 4 neutrons have a valency of ___.