Explanation:Covalent Bonds:Covalent bonds are mostly found in organic compounds.They are non-metallic weaker bonds.Compounds having covalent bonds occur in liquid or gaseous states if in solid, they are soft solids.They are bad conductors of heat and electricity.Compounds having covalent bonds have low melting and boiling points. Covalent compounds are insoluble in water and organic solvents.Covalent bonds are of two types - sigma (strong) and pi (weak).Important PointsCalcium Oxide:Its formula is CaOIt is an ionic compound.It is a white or greyish white solid substance.It can absorb carbon dioxide from the atmosphere easily,Sodium Nitride:Its formula is Na3NIt is an ionic compound.It has a gap that is usually found in semiconductors.It is formed from metal to non-metal interactions.Silicon Carbide:Its formula is SiC.Silicon carbide has a strong covalent bond between them.It is also known as the covalent network solid.It has oxidation resistance and thermal shock resistance.Zinc Sulphide:Its formula is ZnSIt is an ionic compound.It is usually black in colour due to various impurities and is thus used as a pigment.It is used as a window in optics.