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प्रश्न
What do you observe when :
an iron nail is kept in tap water for few days
उत्तर
We observe reddish brown coating on the nail called rust (entirely new substance) is chemical change.
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संबंधित प्रश्न
Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.
\[\ce{NH3_{(g)} + HCl_{(g)} -> NH4Cl_{(s)}}\]
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Explain the type of reactions on the basis of the direction of reaction.
How is a strong electrolyte different from a weak electrolyte?
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Explain by writing a word equation.
Limestone powder disappears on adding to dilute hydrochloric acids.
What do you observe? When
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Photochemical reaction
Give one example
Name the gases which Turn moist red litmus blue.
Complete the following table and write your observations.
|
Hydrogen sulphide |
Ammonia |
Sulphur dioxide |
Hydrogen chloride |
|
|
Shake the gas with red litmus solution |
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Shake the gas with blue litmus solution |
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|
Apply a burning splint to a gas |
Name: A greenish-yellow gas.
Give a chemical test to distinguish between the following gases.
HCl and Cl2
Represent the addition of dilute sulphuric acid to zinc by means of a chemical equation. State the function of the arrow between the reactants and products.
Give a word equation for the following reaction.
An exothermic reaction where both the reactants are gases, one of which is oxygen.
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A characteristic change of colour is seen when a piece of iron is added to copper [II] sulphate solution.
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A coloured substance which leaves a black residue and evolves two gases one of which is acidic and coloured and the other neutral and colourless.
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\[\ce{Ag->Ag+}\]
Select the correct answer from the options given below:
State the gaseous product formed, when
An active metal reacts with dilute sulphuric acid.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Copper nitrate.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Zinc carbonate.
Circle the odd one out. Give reason for your choice
______ is not a chemical change.
What is the use of indicator?
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Can you change rust back into iron by some simple method?
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______ is a chemical substance is used in whitewashing.
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