There are 3 significant figures
Answer:
The period number tells which is the highest energy level occupied by the electrons.
Explanation:
- The period number (denoted by n) is the outer energy level that is occupied by electrons in an atom.
- The period number that an element is in, is the number of energy levels that the element has.
- When we move across a period from left to right in a periodic table the number of electrons in atoms increases within the same orbit.
Explanation:
option 3 is right I. e NA