Which of the following is the atomic number of a metal?

Which of the following compounds is used as a fire extinguisher?

In what ways does lithium show similarities to magnesium in its chemical behaviour?

The causticization process is used for the preparation of:

Alkali metals possess metallic lustre when freshly cut because

An ionic hydride of an alkali metal has significant covalent character and is almost unreactive towards oxygen and chlorine. This is used in the synthesis of other useful hydrides. Write the formula of this hydride. Write its reaction with $Al_2Cl_6$.