Why methane and silicon dioxide have different melting point​

Methane is made up discrete molecules hence it adopts a simple molecular structure with weak vanderwaals forces of attraction while Silicon dioxide adopts a giant covalent structure with strong silicon to oxygen bonds.

Hence Silicon dioxide has a high melting point than methane.

adding or remove a gaseous reactant or product changes the concentrations. if the concentration of reactant or product is increased, the system will shift away from the side in which concentration was increased (i.e. if the concentration of reactants is increased, the system will shift toward the products. if more products are added, the system will shift to form more reactants). conversely, if the concentration of reactant or product is decreased, the system will shift toward the side in which concentration was decreased (i.e. if reactants are removed, the system will shift to form more reactants. if the concentration of products is decreased, the equilibrium will shift toward the products).

explanation:

the product of the pressure and volume is also constant