The correct answer is C. Both 1 and 2.
Sodium silicate and sodium sulphate are mixed as detergents in washing powders to maintain both the dryness of the powder and the basicity of the powder.
Sodium silicate is a water-soluble salt that is used as a thickener, binder, and dispersant in a variety of products, including washing powders. It helps to keep the powder dry and prevents it from caking.
Sodium sulphate is a water-soluble salt that is used as a builder in washing powders. It helps to soften water and improve the cleaning action of the detergent. It also helps to maintain the basicity of the powder, which is important for preventing the build-up of limescale in washing machines.
Without sodium silicate and sodium sulphate, washing powders would be less effective and would not be able to maintain their dryness and basicity.