Question

Which of the following groups contain mostly radioactive elements?
a) Actinoids
b) Alkaline earth metals
c) Halogens
d) Non metals

Answer 1

Hint: We need to know that in chemistry, periodic tables play a vital role. Now we are using a modern periodic table. This modern periodic table consists of totally $$118$$ elements. In the periodic table there are totally $$18$$ columns and $$7$$ rows. The columns are called groups. Hence, $$18$$ groups in the periodic table. The rows are called periods. Hence, totally $$7$$ period in the table.

Complete answer:
We know that in the modern periodic table metallic atoms are placed on the left side of the table and non-metallic atoms are placed on the right side of the table. Metalloids and transition elements are placed in between metal and non-metal elements. Below the two rows are there. There are nothing but lanthanides and actinides. These are f-block elements.
Lanthanides and actinides are the group that contain mostly radioactive elements in the periodic table.
According to the above discussion we conclude, actinides are the group that contain mostly radioactive elements in the periodic table.
Hence, Option A is the correct answer because actinides are the group that contain mostly radioactive elements.
Option B is not the correct answer because alkaline earth metals do not have radioactive elements.
Option C is not the correct answer because the halogen group does not contain any radioactive elements.
Option D is not the correct answer because non-metals are the group that does not contain mostly radioactive elements.

Hence, Option A is the correct answer because actinides are the group that contain mostly radioactive elements.

Note:
In the world there are a lot of elements in various forms. For study and developing purposes, classification happens. Periodic table used to study the elements in easy form. If one new element is discovered, it means, based on the physical and chemical properties we placed in the periodic table.
In general, modern periodic table ordering is based on the atomic number of the atoms. The lowest atomic number starting from the first and followed by a higher atomic number.
Depending on the energy level of the outermost shell in the atoms, periods are classified and place the atom in respect period. Depending on the electrons shielding and size and physical behaviour of the atom, groups are coming.