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प्रश्न
Define corrosion.
Define the following term:
Corrosion
उत्तर १
When the surface of a metal is attacked by air, moisture or any other substance around it, the metal is said to corrode and the phenomenon is known as corrosion.
उत्तर २
Corrosion is an electrochemical process in which a metal is oxidised to metal oxide or another salt of the metal by losing electrons to oxygen or another electronegative element and forms a coating on the metal surface. The rusting of iron, the tarnishing of the silver surface, and the surface of copper and bronze running green are some examples of corrosion.
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.
Give one example of an oxidation-reduction reaction which is also a displacement reaction.
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.
In order to prevent the spoilage of potato chips, they are packed in plastic bags in an atmosphere of:
(a) Cl2
(b) H2
(c) N2
(d) O2
The process of respiration is:
(a) an oxidation reaction which is endothermic
(b) a reduction reaction which is exothermic
(c) a combination reaction which is endothermic
(d) an oxidation reaction which is exothermic
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
Define oxidation.
Give scientific reason.
It is reccommended to use air tight container for storing oil for long time.
Compare hydrogen and halogens on the basis of:
reaction with oxygen
Why this reaction is considered a reversible reaction?
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.
Mg + 2HCl → MgCl2 + H2
State whether the following conversion is oxidation or reduction:
PbO2 + SO2→ PbSO4
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:
Cl2 + 2Br- → Br2 + 2Cl-
A metal oxide that is reduced by hydrogen is
Name:
a liquid that is an oxidizing agent as well as a reducing agent.
Name:
a gas that is oxidizing as well as a reducing agent.
Name:
a solid that is an oxidizing agent.
Complete and balance the following equation:
Zn +_________________→ZnCl2 + H2
Complete and balance the following equation:
CuO +__________→ Cu +___________
State a reason why, when hydrogen is passed over heated copper oxide, the resultant product formed, differs in colour from the original reactant.
Give two test for an oxidising agent.
When Ag is exposed to air it gets a black coating of ____________.
Identify the oxidising agent (oxidant) in the following reactions.
`"CuO" + "H"_2 -> "Cu" + "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?
Why do we store silver chloride in a dark coloured bottle?
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.
The tendency of atoms to have eight electrons in the outer shell is known as ______.
The sum of the oxidation number of all atoms in a compound is ______.
Identify the following reactions as oxidation/reduction/redox reaction
2Mg +O2 → 2MgO
Define oxidation number.
Find the oxidation number of the element in the following compound.
Ca in CaH2
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
