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प्रश्न
Define corrosion.
Define the following term:
Corrosion
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उत्तर १
When a metal is attacked by substances around it, such as moisture, acids, etc., it is said to corrode, and this process is called corrosion.
उत्तर २
Corrosion is an electrochemical process in which a metal is oxidised to a metal oxide or another salt of the metal by losing electrons to oxygen or another electronegative element, forming a coating on the metal surface.
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.
\[\ce{4Na(s) + O2(g) -> 2Na2O(s)}\]
A shiny brown-coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black-colored compound formed.
The addition of hydrogen to a substance is called ______ whereas removal of hydrogen is called ______.
Give one example of an oxidation-reduction reaction which is also a displacement reaction.
Define the following in terms of gain or loss of hydrogen with one example:
Oxidation
In the context of redox reactions, the removal of hydrogen from a substance is known as ______.
You are given the following chemical equation:
\[\ce{Mg_{(s)} + CuO_{(s)} -> MgO_{(s)} + Cu_{(s)}}\]
This equation represents:
Hydrogen burns with a ______ flame and ______ sound is heard.
Name the following:
The process in which oxygen is added or hydrogen is removed.
Define reduction.
Define redox reaction.
MULTIPLE CHOICE QUESTIONS
The process of adding oxygen to a substance is called
- oxidation.
- reduction.
- displacement.
- hydrogenation.
The electron releasing tendency of zinc is ______ than that of copper.
How would you change a metal like Cu into its ions?
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
Identify from the reaction the reactants that undergo oxidation and reduction.
Fe + S → FeS
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
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
Why this reaction is considered a reversible reaction?
State, giving reason, whether the substances printed in bold letters have been oxidized or reduced.
PbO + CO → Pb + CO2
State whether the following conversion is oxidation or reduction:
2Cl- - e-→ Cl2
In the following reaction: A+ + B → A + B+. Write half-reactions for this reaction and name:
- oxidizing agent
- substance oxidized
- reducing agent
Write the equation in the ionic form
CuSO4(aq) + Fe(s)→ FeSO4(aq) + Cu(s)
For the reaction PbO + H2→ Pb + H2O, which of the following statements is wrong?
Name:
an oxidizing agent that does not contain oxygen.
Name:
a substance that oxidizes concentrated HCl to chlorine.
Name:
a gas that is oxidizing as well as a reducing agent.
Complete and balance the following equation:
H2 + S → ___________
Give two tests for a reducing agent.
Select the correct answer from the symbol in the bracket.
The element, which like hydrogen is a strong reducing agent.
Write chemical formula for rust.
Balance the given chemical reaction as per the instructions below.
\[\ce{NaOH + H2SO4 -> Na2SO4 + H2O}\]
Oxidation means losing electrons then what is reduction?
Oxidising agents are also called as ______ because they remove electrons form other substances.
Rusting of iron involves a chemical reaction which is a combination of:
\[\ce{MnO2 + 4HCl -> + 2H2O + Cl2}\]
Identify the substance oxidized in the above equation.
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
`"V"_2"O"_5 + 5"Ca" -> 2"V" + 5"CaO"`
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?
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.
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?
Write a short note on oxidizing and reducing agents.
The tendency of atoms to have eight electrons in the outer shell is known as ______.
The tarnishing of metals is due to the formation of ______.
______ is a metal that has a high resistance to corrosion.
Identify the following reactions as oxidation/reduction/redox reaction
CuO+H2 → Cu+H2O
What are reducing agents? Give examples.
What is rancidity?
Find the oxidation number of the element in the following compound.
Mg in MgO
Identify the type of chemical reaction given below:
\[\ce{2Mg + O2 -> 2MgO}\]
When hydrogen gas is passed over black copper oxide, a reddish-coloured layer of copper is formed.
Answer the questions that follow based on this reaction.
- Write the equation.
- What type of reaction is it?
- Complete the blanks:
In this reaction, an oxygen atom goes away from CuO (copper oxide), which means that ______ of copper oxide takes place, whereas a hydrogen molecule takes up an oxygen atom and water (H2O) is formed, meaning ______ of hydrogen takes place.
The metallic oxide which can be reduced by using common reducing agents is ______.
