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प्रश्न
It is recommended to use air tight containers for storing oil for a long time.
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उत्तर
When oil or ghee is left out for an extended period of time, it oxidises and becomes rancid due to air oxidation. Antioxidants are used to prevent rancidity in foods cooked in oil or ghee. The oxidation reaction of food can also be slowed by storing it in an air tight container.
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संबंधित प्रश्न
Corrosion can be prevented by using ……………. solution.
Identify the substances that are oxidised and the substances that are reduced in the following reaction.
\[\ce{4Na(s) + O2(g) -> 2Na2O(s)}\]
Explain the following in term Oxidation of gain or loss of oxygen with two example.
A shiny brown-coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black-colored compound formed.
What are anti-oxidants? Why are they added to fat and oil containing foods?
In the following reaction between lead sulphide and hydrogen peroxide:
PbS (s) + 4H2O2(aq) → PbSO4(s) + 4H2O(1)
(a) which substance is reduced?
(b) Which substance is oxidised?
Give an example of an oxidation reaction.
Give one example of an oxidation-reduction reaction which is also a combination reaction.
Define oxidation in terms of gain or loss of hydrogen with one example.
Define reduction in terms of gain or loss of hydrogen with one example.
When a magnesium ribbon is heated, it burns in air to form magnesium oxide. Write a balanced chemical equation for this reaction. Name (i) substance oxidised, and (ii) substance reduced.
Indicate which of the following statement is true and which is false:
The removal of hydrogen from a substance is called reduction.
Define reduction.
MULTIPLE CHOICE QUESTIONS
The process of adding oxygen to a substance is called
- oxidation.
- reduction.
- displacement.
- hydrogenation.
Electrolysis is a redox process. Explain.
Identify from the reaction the reactants that undergo oxidation and reduction.
\[\ce{NiO + H2 -> Ni + H2O}\]
Explain the following in term of gain or loss of oxygen with two examples.
Oxidation
Compare hydrogen with alkali metals on the basis of:
Oxide formation
Give the general group study of hydrogen with reference to
reducing power
Compare hydrogen and halogens on the basis of:
reaction with oxygen
Why this reaction is considered a reversible reaction?
State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.
Mg + 2HCl → MgCl2 + H2
State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.
Cl2 + H2S → 2HCl + S
State whether the following conversion is oxidation or reduction:
K → K+ + e-
Divide the following reactions into oxidation and reduction half-reaction:
Zn + Cu2+ → Cu + Zn 2+
Name:
an oxidizing agent that does not contain oxygen.
Complete and balance the following equation:
Zn +_________________→ZnCl2 + H2
With reference to oxidation & reduction reaction – complete the statement given by filling in the blanks with only the words (a) Addition (b) Removal.
‘Oxidation is a chemical reaction involving ____ of oxygen to a substance or ____ of hydrogen from a substance. Reduction on the otherhand involves ____ of hydrogen to a substance or ____ of oxygen from a substance.
Explain the term redox reaction with an example involving the reaction of hydrogen sulphide with chlorine.
Give two test for an oxidising agent.
The process of reduction involves ____________.
In the reaction of iron with copper sulphate solution:
CuSO4 + Fe → Cu + FeSO4
Which option in the given table correctly represents the substance oxidized and the reducing agent?
| OPTION | Substance Oxidized | Reducing Agent |
| A | Fe | Fe |
| B | Fe | FeSO4 |
| C | Cu | Fe |
| D | CuSO4 | Fe |
Identify the reducing agent in the following reactions
`4"NH"_3 + 5"O"_2 -> 4"NO" + 6"H"_2"O"`
Identify the reducing agent in the following reactions -
`"H"_2"O" + "F"_2 -> "HF" + "HOF"`
Identify the oxidising agent (oxidant) in the following reactions
`2"Mg" + "O"_2 -> 2"MgO"`
Which among the following are physical or chemical change?
Evaporation of petrol
Which among the following are physical or chemical change?
Curding of milk
Which among the following are physical or chemical change?
Sublimation of solid ammonium chloride
During the reaction of some metals with dilute hydrochloric acid, following observations are made.
The temperature of the reaction mixture rises when aluminium (Al) is added.
Explain this observation giving suitable reason.
Why do we store silver chloride in a dark coloured bottle?
On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, white precipitate is obtained :
- Write a balanced chemical equation for the reaction involved.
- What other name can be given to this precipitation reaction?
- On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?
The tarnishing of metals is due to the formation of ______.
The sum of the oxidation number of all atoms in a compound is ______.
Identify the following reactions as oxidation/reduction/redox reaction
CuO+H2 → Cu+H2O
What is rancidity?
Define oxidation number.
Find the oxidation number of the element in the following compound.
Zn in ZnSO4
Find the oxidation number of the element in the following compound.
Ca in CaH2
Find the oxidation number of the element in the following compound.
A1 in AlCl3
Identify the type of chemical reaction given below:
\[\ce{2Mg + O2 -> 2MgO}\]
State whether the given chemical reaction is a redox reaction or not. Justify your answer.
\[\ce{MnO_2 + 4HCl->MnCl_2 +2H_2O + Cl_2}\]
Metals are good ______.
The metallic oxide which can be reduced by using common reducing agents is ______.
