Question 10
for scientists, an element (like gold) is defined by

For scientists, an element is defined by THE NUMBER OF PROTON IT CONTAINS.

Explanation:

In science, an element is defined as the simplest chemical substance that can not be further broken down by mean of chemical reaction. Each element is made up of atoms and the atoms have specific number of electrons and protons. The number of proton that an element has determine its atomic number. For neutral elements the number of proton and electron are always the same.

Today, many chemical elements have been identified and one of them is gold. Gold with chemical symbol Au has atomic number 79, this implies that the neutral gold has 79 electrons and 79 protons.