. A standard dry cell has an output voltage of A. 1.5 VDC. B. 1.1 VDC. C. 1.2 VDC. D. 2.0 VDC.
1 answer:
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Answer : The oxidation-reduction reactions are:
I. reaction of a metal with a nonmetal
II. synthesis
III. combustion
Explanation :
Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.
Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.
Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.
I. Reaction of a metal with a nonmetal :
When sodium react with chlorine gas then it react to give sodium chloride.
In this reaction, the oxidation state of sodium changes from (0) to (+1) and shows oxidation and the oxidation state of chlorine changes from (0) to (-1) and shows reduction. So, It is an oxidation-reduction reaction.
II. Synthesis reaction :
A chemical reaction where multiple substances or reactants combine to form a single product.
When hydrogen react with oxygen then it react to give water.
In this reaction, the oxidation state of hydrogen changes from (0) to (+1) and shows oxidation and the oxidation state of oxygen changes from (0) to (-2) and shows reduction. So, It is an oxidation-reduction reaction.
III. Combustion reaction :
A chemical reaction in which a hydrocarbon reaction with the oxygen to give product as carbon dioxide and water.
When methane react with oxygen gas then it react to give carbon dioxide and water.
In this reaction, the carbon of methane gain oxygen and shows oxidation and the oxygen gas gain hydrogen and shows reduction. So, It is an oxidation-reduction reaction.
IV. Precipitation reaction :
It is defined as the reaction in which an insoluble salt formed when two aqueous solutions are combined.
The insoluble salt that settle down in the solution is known an precipitate.
It is a double displacement reaction. So, it is not an oxidation-reduction reaction.
V. Decomposition reaction :
A chemical reaction in which the the larger molecule decomposes to give two or more smaller molecules.
The oxidation state remains same on reactant and product side. So, it is not an oxidation-reduction reaction.
Answer : The balanced chemical equation is,
Explanation :
Balanced chemical equation : It is defined as the number of atoms of individual elements present on the reactant side must be equal to the number of atoms of individual elements present on product side.
The given unbalanced chemical reaction is,
This chemical reaction is an unbalanced reaction because in this reaction, the number of atoms of individual elements are not balanced.
In order to balanced the chemical reaction, the coefficient 2 is put before the , the coefficient 3 is put before the
and the coefficient 4 is put before the
.
The energy evolved in this reaction =
Thus, the balanced chemical reaction will be,