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JEE · NEET Previous Year Question

The oxidation number of an element in a compound is evaluated on the basis of certain rules. Which of the following rules is not correct?
1.The oxidation number of hydrogen is always +1 .
2.The algebraic sum of all the oxidation numbers of all elements in a compound is zero.
3.An element in the free or the uncombined state bears oxidation number zero.
4.In all its compounds, the oxidation number of fluorine is -1 .

Topic: JEE PYQ

Answer: A. Full step-by-step solution below.

  1. A1
  2. B2
  3. C3
  4. D4

Correct answer: A

Solution

(a) In alkali and alkaline earth metal hydride oxidation state of hydrogen atom is -1 .

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