Why must the sodium hydroxide solution be standardized before use? why can’t a solution of known concentration just be prepared immediately before use?

It is a highly hygroscopic material so it could have water inside even when solid.

Explanation:

Hello,

It turns out that sodium hydroxide is a highly hygroscopic material, it means that it is able to catch as much water as it can from the environment and subsequently attach it to its structure even when solid, that is why a simple weight by a balance is not enough to determine the exact weight of a pure sodium hydroxide sample. Consequently, a strict standardization must be performed before its usage, since an error in the sodium hydroxide's concentration could be exhibited due to the misestimation.

Best regards.

catya that's not even a b or c