<span>Es un planeta rocoso.</span>
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.
Since 1970, fertility rates have declined in both more developed and less developed countries.
Explanation:
The fertility rates have had some big swings, both up and down in the past century. Everyone is familiar with the ''baby boom'' period, when the fertility rates around the world all skyrocketed, which resulted in rapid growth of the global population. This all started to change though, and from the 1970's onward the fertility rates have started dropping and still do.
It is not just the developed countries that experience this trend, but the less developed as well. The differences is mainly that the developed countries have fertility rates that are below the sustainability point, while the less developed still have relatively high fertility rates and their population still grown. In the manner in which things are going, it is expected that the global population will stop growing in about two or three decades.
Countries that have low fertility rates are:
Countries that have relatively high fertility rates are:
- Zimbabwe
- Pakistan
- Bangladesh
- Nigeria
Learn more about the difference between developed and developing countries brainly.com/question/12890963
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