393. Argon is the third largest constituent of air (followed by N2 & O2). Its percentage by volume in air is
394. Sulphuric acid completely saturated with sulphur trioxide is called
395. Main constituent of limestone is
396. Systemic insecticides
397. Starting raw material for the manufacture of alum is
398. Parathion and Malathion are
399. BHC (Benzene hexachloride) is made by the chlorination of benzene
