Erosion of farmland, overuse of both surface and groundwater, dwindling supplies of finite fossil fuels, and escalating extinction of plant and animal species imperil the ability of the earth's resources to meet the needs of such enormous numbers of humans. The food situation worldwide is becoming critical
Answer:
Quartz is not pure in this rock.
Explanation:
When quartz shows effervescence in contact with an acid, it means that it is not in its pure state, but rather related to other substances that may be cementing the quartz. This effectiveness is caused by substances that do not react like quartz, such as calcite.
In this case, we can conclude that in relation to the calcium-rich rock shown in the question above, the calcium is not pure, but it is likely to be related to calcite, or other material that does not react to acid.
