The oxidation number of chromium in potassium dichromate is
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Solution
Let x= oxidation no. of Cr in K2Cr2O7.
∴(2 × 1) + (2 × x) + 7 (– 2) = 0
or 2 + 2x– 14 =0 or x= + 6.
Which will reduce zinc oxide to zinc ?
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Solution
Mg which is placed at higher position in electrochemical series will reduce zinc oxide to zinc.
In which of the following reactions, there is no change in valency?
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Solution
In this reaction, none of the elements undergoes a change in oxidation number or valency.
Phosphorus has the oxidation state of +3 in
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Solution
O.N. of P in H3PO3(phosphorous acid)3 × 1 + x+ 3 × (– 2) = 0 or x = + 3 In orthophosphoric acid (H3PO4) O.N. of P is +5, in hypophosphorous acid (H3PO2) it is +1 while in metaphosphoric acid (HPO3),it is +5,
Which of the following cannot act as reducing agent?
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Solution
In all the given compounds oxidation number of non metal is + 4. As C belongs to group IV and it is in its maximum oxidation state. So, reduction in oxidation number of nonmetal is not possible only in CO2. As we know that reduction is always accompained by an increase in oxidation number of reducing agent. So,CO2 cannot acts as reducing agent among the given choices.
Oxidation number of N in HNO3 is :
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Solution
Let the oxidation no. of N in HNO3= x
∴1 + x+ (3 × –2) = 0
∴x= + 5
When Sn2+ changes to Sn4+ in a reaction
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Solution
Sn2+→Sn4++ 2e-. In this reaction Sn2+ change in Sn4+ it is called an oxidation reaction.
The conversion of sugar C12H22O11→CO2is
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Solution
Neither oxidation nor reduction
The element that is easiest to be reduced:
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Solution
Ag is easiest to be reduced among the given choices because its reduction potential is highest among the given choices.
In the reaction 3Mg + N2→Mg3N2
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Solution
In the given reaction oxidation state of Mg is changing from 0 to +2 while in nitrogen it is changing from 0 to– 3. So oxidation of Mg and reduction of nitrogen takes place.