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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
The chemical formula for rust is.............. .
Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
Identify the substances that are oxidised and the substances that are reduced in the following reaction.
\[\ce{4Na(s) + O2(g) -> 2Na2O(s)}\]
Which of the statements about the reaction below are incorrect?
\[\ce{2PbO(s) + C(s) → 2Pb(s) + CO2(g)}\]
- Lead is getting reduced.
- Carbon dioxide is getting oxidised.
- Carbon is getting oxidised.
- Lead oxide is getting reduced.
Write the chemical formula of rust.
What are anti-oxidants? Why are they added to fat and oil containing foods?
Fill in the following blanks with suitable words:
The addition of oxygen to a substance is called ......... whereas removal of oxygen is called ........
Fill in the following blanks with suitable words:
The addition of hydrogen to a substance is called ........ whereas removal of hydrogen is called .......
When a magnesium ribbon burns in air with a dazzling flame and forms a white ash, is magnesium oxidised or reduced? Why?
Give one example of an oxidation-reduction reaction which is also a displacement reaction.
You are given the following chemical equation:
Mg (s) + CuO (s) → MgO (s) + Cu (s)
This equation represents:
(a) decomposition reaction as well as displacement reaction
(b) combination reaction as well as double displacement reaction
(c) redox reaction as well as displacement reaction
(d) double displacement reaction as well as redox reaction
Fill in the blank
Oxidation is the removal of ......................and addition of ....................
Define an oxidation reaction.
Define redox reaction.
The electron releasing tendency of zinc is ______ than that of copper.
Identify from the following reaction the reactants that undergo oxidation and reduction.
\[\ce{2Ag2O → 4 Ag + O2 \uparrow}\]
Explain the following in term of gain or loss of oxygen with two examples.
Reduction
In what respect does hydrogen differ from:
alkali metals
Give the general group study of hydrogen with reference to
burning
Give the general group study of hydrogen with reference to
reducing power
Is it essential that oxidation and reduction must occur side by side in a chemical reaction? Explain
State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.
H2S + Cl2→ 2HCl + S
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:
Cu2+ + 2 e-→ Cu
Divide the above equation into oxidation and reduction half-reactions.
For the reaction PbO + H2→ Pb + H2O, which of the following statements is wrong?
Name:
a liquid that is an oxidizing agent as well as a reducing agent.
Name:
a solid that is an oxidizing agent.
Complete and balance the following equation:
Fe + H2O →___________+____________
State the condition and give balanced equation for the conversion of coke to water gas.
Explain the term oxidation in term of addition and removal of oxygen/hydrogen with a suitable example.
Explain the term reduction in term of addition and removal of oxygen/hydrogen with a suitable example.
Give two tests for a reducing agent.
Write chemical formula for rust.
Explain the following reaction with their balanced chemical equation.
Hydrogen sulphide reacts with sulphur dioxide.
Balance the given chemical reaction as per the instructions below.
\[\ce{NaOH + H2SO4 -> Na2SO4 + H2O}\]
Oxidation means losing electrons then what is reduction?
Identify the reducing agent in the following reactions
`2"H"_2 + "O"_2 -> 2"H"_2"O"`
Identify the oxidising agent (oxidant) in the following reactions
`"Pb"_3"O"_4 + 8"HCl" -> 3"PbCl"_2 + "Cl"_2 + 4"H"_2"O"`
Grapes hanging on the plant do not ferment but after being plucked from the plant can be fermented. Under what conditions do these grapes ferment? Is it a chemical or a physical change?
Which among the following are physical or chemical change?
Curding of milk
During the reaction of some metals with dilute hydrochloric acid, following observations are made.
The reaction of sodium metal is found to be highly explosive
Explain this observation giving suitable reason.
Zinc liberates hydrogen gas when reacted with dilute hydrochloric acid whereas copper does not. Explain why?
You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dilute HCl, dilute HNO3, ZnCl2 and water. In which of the above containers, can these solutions be kept?
The formation of brown colour on the freshly unit surface of vegetables and fruits is because ______ of organic compounds present in them.
The tarnishing of metals is an example of ______ reaction.
Define oxidation number.
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.
N in NH3
In the redox reaction:
MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
State whether the given chemical reaction is a redox reaction or not. Justify your answer.
\[\ce{MnO_2 + 4HCl->MnCl_2 +2H_2O + Cl_2}\]
State the change in colour observed in following case mentioning the reason:
Copper powder is strongly heated in air.
