Answer:
4 for C in CH4
+4 for C in CO2
-2 for O in all substances
+1 for H in both CH4 and H2O
option 1,2,3 and 4 are correct. Option 5 is not correct
Explanation:
Step 1: Data given
Oxidation number of H = +1
Oxidation number of O = -2
Step 2: The balanced equation
CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
Step 3: The oxidation numbers
-4 for C in CH4
⇒ Oxidation number of H = +1
⇒ 4x +1 = +4
C has an oxidation number of -4
This is correct.
+4 for C in CO2
⇒ Oxidation number of O = -2
⇒ 2x -2 = -4
C has an oxidation number of +4
This is correct.
-2 for O in all substances
⇒ this is correct, the oxidation number of O is always -2 (except in H2O2 and Na2O2)
This is correct.
+1 for H in both CH4 and H2O
⇒ this is correct, the oxidation number of H is always +1 (except in metal hydrides).
This is correct.
+4 for O in H2O
⇒ Oxidation number of H = +1
⇒ 2x +1 = +2
The oxidation number of O is -2
This is not correct
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