Bacteria in general grow optimally when the pH is around 7 (5-9 let's say). That is not to say that there are not bacteria that grow in extremely acidic conditions, like in our stomach, or others in extremely basic conditions, like the conditions near volcanoes. Nonetheless, bacteria that grow in food prefer acidic environments over basic ones and usually cannot tolerate the acidity of fruits which is around 4 pH for the most acid ones. For example, stuff like milk and bread that have a pH from 5-6 are prime examples of food where bacteria would thrive. Thus, the correct answer would be b.
Answer:
The Laura tried to grow micro-organisms in culture broth medium in Petri-plates but the microbial growth was not observed even on the fourth day of culture which could be due to:
1. Laura could have not provided the correct broth medium maintaining the with pH and salt concentrations.
2. Microorganisms did not get optimal growth conditions.
3. The bacterial source could have died after the collection which could have lysed after their death and thus no longer visible.
Acid rain, or acid deposition, is a broad term that includes any form of precipitation with acidic components, such as sulfuric or nitric acid that fall to the ground from the atmosphere in wet or dry forms. This can include rain, snow, fog, hail or even dust that is acidic.
