40 milliliters 16% hydrochloric acid solution must be mixed with what amount of water to produce a 4% hydrochloric acid solution? explain clearly. is there a formula explan

Look at it this way, in 40ml there is 16% HCl, this is 6.4ml of HCl. If you wanted 4% HCl, that would be 1.6ml of HCl; however, you want to add water not remove HCl for this question.

A simple way to solve this is to keep the HCl amount the same (6.4ml) and double the water content. Here’s what I mean:
6.4m/80ml=0.08 or 8% HCl.

To find the final solution double the amount of water.
6.4ml/160ml=.04 or 4% HCl

Hope I helped!

The only number less than 8 that can equal 12 would be 6, 36 is the dividend