Question

What is the pH of rain water during acid rain?
1. More than 5.6
2. Between 6 to 8.5
3. Equal to 5.6
4. Less than 5.6

Answer 1

Correct Answer - Option 4 : Less than 5.6

The correct answer is Less than 5.6.

• Clean rain has a pH value of between 5.0 and 5.5, which is slightly acidic.
  • However, when rain combines with sulfur dioxide or nitrogen oxides—produced from power plants and automobiles—the rain becomes much more acidic.
  • Typical acid rain has a pH value of 4.0.

• Water pH is the number of free hydrogen ions in a given sample, and the scale ranges from 0 to 14, with numbers below 7 being acidic.
  • Each level down the scale represents a tenfold increase in hydrogen ions, so a pH of 5 has ten times more ions than a pH of 6.
  • Normally, lakes will be neutral, pH levels between 6 and 8, but lakes with pH below 5 are considered acidic. 
  • In addition to acid rain, acidic rainfall leeching through soils that lack acid-buffering capability will eventually wind up in streams and lakes.
  • Normally, lake water contains bicarbonates and other compounds that have the ability to buffer their pH levels, but acid rain, in particular, disrupts this ability.