Alkali metals are very reactive chemically.

This rock is radioactive, so care must be taken when handling it.

Francium is a radioactive alkali metal that is hardly present in nature.

His existence enriches my life.

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In this chemical reaction, alkali is needed.

Alkaline earth metals are located in Group 2 of the periodic table.

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This metal is very hard.

Sufficient caution is necessary when handling radioactive materials.