Question

finding clean drinking water is a problem in many parts of the world. as a result, scientists have increasingly turned their efforts to creating water purifying systems. for example, one team tackled the puzzle of turning salt water into drinking water. they used low - cost, solar - powered stills and carbon - dipped paper to remove salt and other pollutants. another team focused on harmful bacteria in lake water. the team discovered an easy fix: break off a branch from a pine tree, remove the bark, and slowly pour the water over the branch. the sapwood filters out more than ninety - nine percent of the e. coli bacteria. another group of researchers concentrated on arsenic, one of the most common pollutants. they found that water treated with biochar, made from hickory chips with added lime, was safe to drink.
match the problems with their solutions.
sapwood can clean the water. a solar still with carbon - dipped paper can clean the water.
biochar can clean the water
problem solution
some water has salt in it.
some water has bacteria in it.
some water has arsenic in it.

Explanation:

• For the problem "Some water has salt in it", the text mentions using "low - cost, solar - powered stills and carbon - dipped paper to remove salt", so the solution "A solar still with carbon - dipped paper can clean the water" matches.
• For the problem "Some water has bacteria in it", it says "the sapwood filters out more than ninety - nine percent of the E. coli bacteria", so "Sapwood can clean the water" is the right match.
• For the problem "Some water has arsenic in it", it states "water treated with biochar... was safe to drink", so "Biochar can clean the water" is the correct match.

Answer:

Some water has salt in it - A solar still with carbon - dipped paper can clean the water.
Some water has bacteria in it - Sapwood can clean the water.
Some water has arsenic in it - Biochar can clean the water.