Answer:
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Explanation:
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Answer:
c. selenium
Explanation:
sulfur and selenium are in the same group
<span>Energy of an electromagnetic wave depends on it's "Frequency"
Hope this helps!</span>
Answer: C. unknown element he predicted would have properties similar to those of aluminum.
Explanation: Mendeleev arranged the elements in order of increasing atomic masses. He left spaces for the elements that were predicted to exist, but were not discovered.
One space was left below Aluminum where an element of mass 70 was predicted to exist with properties similar to Aluminum. It was referred to as eka-Aluminum.
Later it was named as gallium.
