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lord [1]
2 years ago
14

Which best describes an element?

Chemistry
2 answers:
maxonik [38]2 years ago
6 0

Answer:

An impure substance

Explanation:

Substance means: hard surface example: salt,corals,coal.

joja [24]2 years ago
4 0
An element is a pure substance
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Answer:

0.42%

Explanation:

<em>∵ pH = - log[H⁺].</em>

2.72 = - log[H⁺]

∴ [H⁺] = 1.905 x 10⁻³.

<em>∵ [H⁺] = √Ka.C</em>

∴ [H⁺]² = Ka.C

∴ ka = [H⁺]²/C = (1.905 x 10⁻³)²/(0.45) = 8.068 x 10⁻⁶.

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