Quiz1 Science Prep.1 2nd term U.1L.2 part 1 Chemical compounds

Choose:
The valency of hydroxide group is ...........

Choose:
The valency of oxygen element is ...........

Choose:
The valency of sodium element is ...........

Choose:
The valency of argon element is ...........

Put true or false:
.The valency of an element its atomic number is 20 will be monovalent