Which of the following fuels has the highest calorific value?

$(a)$ Show the formation of $MgO$ by the transfer of electrons.
$(b)$ Name the cation and anion.
$(c)$ Write three properties of ionic compounds.

What effect does dihydrogen gas $(H_2)$ have on litmus paper?

Which metal can be beaten into very thin foils?

$A$ metal $E$ is stored under kerosene oil. When a small piece of it is left open in the air,it catches fire. When the product formed is dissolved in water,it turns red litmus blue.
$(i)$ Name the metal $E$.
$(ii)$ Write the chemical equations for the reaction when it is exposed to air and when the product is dissolved in water.
$(iii)$ Explain the process by which the metal is obtained from its molten chloride.

What type of compounds are formed when reactive metals like sodium and potassium react with dihydrogen?