The elements in the first group of s-block are also known as ________ .

The correct answer is option 1, i.e  Alkali Metals.

EXPLANATION:

• The elements in the first group of s-block are also known as Alkali Metals. These have only one electron in their outermost shell and hence are quite reactive as they easily lose their electron to form bonds with non-metals.

• The elements in the second group of s-block are also known as Alkaline Earth Metals. These have two electrons in their outermost shell and are less reactive than Alkali metals.
• Halogens are the group 17 elements and are placed in the p-block.
• Noble gases are the group 18 elements and are placed in the p-block. These are the least reactive amongst all the elements found in the periodic table as they have a stable configuration.