Which of the following is an example of an element: A) H₃O
B) He
C) Ca₂CO₃
D) CaCl₂
PLEASE ANSWER QUICKLY

He(HELIUM)

Explanation:

He (Helium) is an element as it is pure and cannot be broken into simpler substances.

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~AH1807

acid rain does not usually kill trees directly. instead, it is more likely to weaken the trees by damaging their leaves, limiting the nutrients available to them, or poisoning them with toxic substances slowly released from the soil. the main atmospheric pollutants that affect trees are nitrates and sulphates.