Sodium has low melting and boiling points.

Iodine is the only non-metal which is lustrous.

Albite does not contain lithium.

Sodium thiosulphate forms strong complex with gold ions and it is non-toxic. So, some very refractory substances in gold ore can be leached.

Low ionisation energy makes alkali metals lose their outermost single electron easily to form +ve charged ions or cations. Thus, they are highly reactive in nature.

Mercury is the only metal in liquid form.

Potassium ions have high hydration energy which means that they are highly ionic and dissolve readily in a polar solvent like water and release a great amount of energy which is referred to as hydration energy.

Diamond is the hardest allotropic form of carbon.

Iron is an element.

Potassium cobaltinitrite is also called cobalt yellow and is used in oil and watercolour paintings. It is commonly called 'Aureolin'.

The ionisation energy of Be is quite high. Hence, the energy of flame is not sufficient to excite Be electrons to higher energy level.

Sodium is obtained by electrolysis of the mixture of sodium chloride and calcium chloride.This method is known as Down's process.

In this case, the number of outer orbital electrons is 6.

Sodium oxide is not present in cement at all.

In geometry, a pyramid is a polyhedron formed by connecting a polygonal base and a point called the apex. Each base edge and apex form a triangle. It is a conic solid with polygonal base, like NH₃.

It is a poor conductor of heat and electricity.

This method is used for manufacturing sodium cabonate.

The size of Ba²⁺ ion is the largest of the given options, hence it has the least mobility in aqueous solution.