he number of valence electrons found in an atom of a group A element is equal to:  its atomic number   its mass number   it group number   eight

The number of valence electrons found in an atom of a Group A element is equal to its group number.

Here's why:

1. The periodic table is divided into groups (columns) and periods (rows). Group A elements are also known as the main group elements and include groups 1, 2 and 13 to 18.

2. The group number of a main group element often corresponds to the number of valence electrons. Valence electrons are the electrons in the outermost shell of an atom and are involved in chemical reactions.

3. For example, all elements in Group 1 (also known as alkali metals) have 1 valence electron, elements in Group 2 (alkaline earth metals) have 2 valence electrons, and so on.

4. Therefore, the number of valence electrons of a Group A element is equal to its group number.

Note: This rule does not apply to transition metals (Groups 3-12) and inner transition metals (lanthanides and actinides).