Answer:
- Communication between scientists increased.
- Technological advancements were made.
Step-by-step explanation:
The complete question is
Which answer choices correctly describe why the number of known elements more than doubled by 1861?
Select all that apply.
- Metalworkers began using new metals.
- Communication between scientists increased.
- The American Civil War started.
- Technological advancements were made.
Technological advancement allowed more elements to be properly analysed and classified, and knowledge sharing between scientist by means of communication made it possible for the known number of elements to double by 1861