GCSE / O Levels Chemistry

The elements are arranged in groups and periods in the Periodic Table. Which row is correct? group determined by   period determined by   elements in the Periodic Table are arranged by  A   the number of electrons in the outer shell the number of occupied shells increasing proton number  B   the number of occupied shells the number of electrons in the outer shell increasing mass number  C   the number of electrons in the outer shell the number of occupied shells increasing mass number  D   the number of occupied shells the number of electrons in the outer shell increasing proton number

The Periodic Table | 2023 - M/J - 5070/11 | Q21