Carbon and hydrogen
Sodium and aluminium
Chlorine and oxygen
Potassium and iodine
Sodium is more reactive than magnesium
The attraction between the sodium ion and the chloride ion is weaker than that between magnesium ion and oxide ion.
The melting point of sodium is lower than magnesium.
Ionic bonding is present in sodium chloride while metallic bonding is present in magnesium oxide.
It conducts electricity when molten.
It is gaseous at room temperature.
It can be synthesised from its elements.
It is almost insoluble in water.
1 and 4 only
2 and 4 only
3 and 4 only
The constituents can be separated by physical means.
The elements are always in a fixed proportion by mass,
They have fixed melting and boiling points.
A chemical change takes place during formation of a compound.
They have very high melting points.
A lot of energy is required to overcome the strong electrostatic attraction between the oppositely charged ions.
They face electrostatic repulsion when ions of the same charge are brought together.
There is weak electrostatic attraction between the ions and the negative "sea" of electrons.
They are neither malleable nor ductile
They have low melting and boiling points.
They are poor conductors of electricity
They are solid state at room temperature.