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प्रश्न
Give scientific reason.
It is reccommended to use air tight container for storing oil for long time.
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उत्तर
- When edible oil is left aside for long time, it undergoes air oxidation.
- Due to this, the taste and smell of oil changes and it becomes rancid. If food is cooked in this oil, its taste also changes.
- Thus, the oil will become unfit for consumption.
- The process of oxidation reaction of oil can be slowed down by storing it in air tight container.
Hence, it is recommended to use air tight container for storing oil for long time.
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संबंधित प्रश्न
Identify the substances that are oxidised and the substances that are reduced in the following reaction.
\[\ce{4Na(s) + O2(g) -> 2Na2O(s)}\]
What is meant by rust?
What are anti-oxidants?
In the following reaction between lead sulphide and hydrogen peroxide:
\[\ce{PbS_{(s)} + 4H2O2_{(aq)} -> PbSO4_{(s)} + 4H2O_{(l)}}\]
- Which substance is reduced?
- Which substance is oxidised?
The addition of hydrogen to a substance is called ______ whereas removal of hydrogen is called ______.
Give an example of an oxidation reaction.
When copper powder is heated strongly in air, it forms copper oxide. Write a balanced chemical equation for this reaction. Name
- substance oxidised, and
- substance reduced.
Define the following in terms of gain or loss of hydrogen with one example:
Reduction
When a magnesium ribbon is heated, it burns in air to form magnesium oxide. Write a balanced chemical equation for this reaction. Name
- substance oxidised, and
- substance reduced.
In order to prevent the spoilage of potato chips, they are packed in plastic bags in an atmosphere of ______.
Fill in the blank
In redox reaction oxidation and reduction occur ............................
Name the following:
The process in which oxygen is added or hydrogen is removed.
Define reduction.
MULTIPLE CHOICE QUESTIONS
The process of adding oxygen to a substance is called
- oxidation.
- reduction.
- displacement.
- hydrogenation.
Identify the substances that are oxidised and the substances that are reduced in the following reaction.
\[\ce{CuO_{(s)} + H2_{(g)} -> Cu_{(s)} + H2O_{(l)}}\]
Electrolysis is a redox process. Explain.
Identify from the reaction the reactants that undergo oxidation and reduction.
Fe + S → FeS
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
In what respect does hydrogen differ from:
alkali metals
Give the general group study of hydrogen with reference to
reducing power
Compare hydrogen and halogens on the basis of:
reaction with oxygen
Describe briefly the ionic concept of oxidation and reduction. Give an equation to illustrate.
State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.
PbO + CO → Pb + CO2
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.
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
Name:
an oxidizing agent that does not contain oxygen.
Name:
a gas that is oxidizing as well as a reducing agent.
Complete and balance the following equation:
Zn +_________________→ZnCl2 + H2
Complete and balance the following equation:
Fe + H2O →___________+____________
Explain the term redox reaction with an example involving the reaction of hydrogen sulphide with chlorine.
State what is reducing agent. Give an example of oxidising agent in the gaseous, liquid, and solid form.
Select the correct answer from the symbol in the bracket.
The element, which like hydrogen is a strong reducing agent.
When the positive charge on an ion increases or the negative charge on them decreases it is called as _______.
Explain the following reaction with their balanced chemical equation.
Hydrogen sulphide reacts with sulphur dioxide.
The process of reduction involves ____________.
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
`"Pb"_3"O"_4 + 8"HCl" -> 3"PbCl"_2 + "Cl"_2 + 4"H"_2"O"`
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.
During the reaction of some metals with dilute hydrochloric acid, following observations are made.
Some bubbles of a gas are seen when lead (Pb) is reacted with the acid.
Explain this observation giving suitable reason.
A silver article generally turns black when kept in the open for a few days. The article when rubbed with toothpaste again starts shining.
- Why do silver articles turn black when kept in the open for a few days? Name the phenomenon involved.
- Name the black substance formed and give its chemical formula.
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?
Choose the odd one out and write the reason:
What are redox reactions? Give examples.
What is rancidity?
Define oxidation number.
It is recommended to use air tight containers for storing oil for a long time.
State whether the given chemical reaction is a redox reaction or not. Justify your answer.
\[\ce{MnO_2 + 4HCl->MnCl_2 +2H_2O + Cl_2}\]
A reddish brown metal used in electrical wires when powdered and heated strongly turns black. When hydrogen gas is passed over this black substance, it regains its original colour. Based on this information answer the following questions:
- Name the metal and the black substance formed.
- Write balanced chemical equations for the two reactions involved in the above information
