An aqueous suspension dosage form is prepared which contains 150 mg of drug per ml of suspension. The equilibrium solubility of the drug in water is 11 g/L. The drug in solution undergoes first-order decomposition and decomposes to 75% of the initial concentration in 400 hours. A) Determine the zero-order rate constant.
B) Assuming that the shelf-life of a drug is t10%, calculate the shelf-life.

b.final

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.