Explanation:
4.hydrogen is able to accept or donate electrons,so it is the most versatile storm I the periodic chart
During a scientific study a hypotheses is generally modified or discarded
so for first blank the answer is hypotheses
Now in case of phlogiston theory it was assumed that when a substance catches fire it evolve certain substances known as phlogiston which was later on discarded as there is no such particle. Infact a substane undergoing oxidation may gain weight
Hence in second blank the answer is new evidence didn’t support it,
Answer:

Explanation:
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In this case, since the melting process involves the heat added to the system, the heat of fusion and the mass of water:

Thus, as it has been reported that the heat of fusion of ice is 333.6 J/g, we can compute the melted mass of ice as shown below:

Thus, the ice leftover results:

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Answer:
The chemists such as analytical chemists determine the structure, composition, and nature of substances by examining and identifying their various elements or compounds. These chemists are crucial to the pharmaceutical industry because pharmaceutical companies need to know the identity of compounds that they hope to turn into drugs.