Plzzz fas answerrr Which answer choices correctly describe why the number of known elements more then doubled by 1861

Communication between scientists increased.

Technological advancements were made.

Explanation:

The options:

Metalworkers began using new metals.

 Communication between scientists increased.

 The American Civil War started.

 Technological advancements were made.

The reasons the number of known elements more than double by 1861 would be because technological advancements have been made and communication between scientists increased.

With the advancement in technology, more equipment become available and research became more sophisticated leading to new discoveries. The new discoveries would not have made much difference if they are not adequately communicated to other scientists.  

specific gravity is the density of a substance divided by the density of water. since (at standard temperature and pressure) water has a density of 1 gram/cm3, and since all of the units cancel, specific gravity is usually very close to the same value as density

so "c" is the answer

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