Question

Which of the following cannot be used as a primary standard in the preparation of a solution

Answer 1

Answer:

The primary standard is a compound of sufficient purity from which standard solutions of known normalities can be prepared by direct weighing of it and diluting to a defined volume of solution.

Potassium Dichromate(K2Cr2O7 ) is suitable to be used as a primary standard.It cannot be obtained in very pure form. It readily reacts with any traces of organic material or any other reducing substance in water.