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प्रश्न
What is meant by rust?
उत्तर
Iron reacts with moist air to acquire a coating of a brown flaky substance called rust.
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संबंधित प्रश्न
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.
A shiny brown-coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black-colored compound formed.
When SO2 gas is passed through saturated solution of H2S, the following reaction occurs:
SO2 + 2H2S → 2H2O + 3S
In this reaction, which substance is oxidised and which one is reduced?
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 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 (i) substance oxidised, and (ii) substance reduced.
In the context of redox reactions, the removal of hydrogen from a substance is known as:
(a) oxidation
(b) dehydration
(c) reduction
(d) dehydrogenation
Fill in the blank
Oxidation is the removal of ......................and addition of ....................
Indicate which of the following statement is true and which is false:
The removal of hydrogen from a substance is called reduction.
The colours of aqueous solutions of CuSO4 and FeSO4 as observed in the laboratory are:
(A) pale green and light blue respectively
(B) light blue and dark green respectively
(C) dark blue and dark green respectively
(D) dark blue and pale green respectively
Explain the following in term of gain or loss of oxygen with two examples.
Reduction
State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.
H2S + Cl2→ 2HCl + S
State whether the following conversion is oxidation or reduction:
Cu2+ + 2 e-→ Cu
State whether the following conversion is oxidation or reduction:
2Cl- - e-→ Cl2
Divide the following reactions into oxidation and reduction half-reaction:
Zn + Pb2+→ Pb + Zn 2+
Divide the following reactions into oxidation and reduction half-reaction:
Cl2 + 2Br- → Br2 + 2Cl-
Write the equation in the ionic form
CuSO4(aq) + Fe(s)→ FeSO4(aq) + Cu(s)
A metal oxide that is reduced by hydrogen is
Choose terms from the options given in brackets to complete this sentence.
When CuO reacts with hydrogen,………………… is reduced and ……………….is oxidized to ………………….
(CuO, H2, Cu, H2O)
Name:
a gas that is oxidizing as well as a reducing agent.
Name:
a solid that is an oxidizing agent.
Explain the term redox reaction with an example involving the reaction of hydrogen sulphide with chlorine.
Select the correct answer from the symbol in the bracket.
The element, which like hydrogen is a strong reducing agent.
Oxidation is a process which 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 oxidising agent (oxidant) in the following reactions
`2"Mg" + "O"_2 -> 2"MgO"`
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.
Silver metal does not show any change
Explain this observation giving suitable reason.
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.
What happens when zinc granules are treated with dilute solution of H2SO4, HCl, HNO3, NaCl and NaOH Also write the chemical equations if reaction oçcurs.
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?
What is a redox reaction?
The sum of the oxidation number of all atoms in a compound is ______.
Choose the odd one out and write the reason:
Identify the following reactions as oxidation/reduction/redox reaction
CuO+H2 → Cu+H2O
What are reducing agents? Give examples.
