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प्रश्न
A chemical reaction is generally accompanied by certain external indications or characteristics. These include – change of – (a) colour (b) state (c) smell (d) evolution of gas (e) formation of precipitate (f) evolution or absorption of heat. With reference to change of colour – state the change in colour seen when the following are heated – copper carbonate.
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उत्तर
Change of colour — In certain chemical reactions a change of colour is seen to be observed. Heat on substances to observe change in colour of reactants and products.
Heat on:
Copper carbonate CuCO3 → CuO + CO2[g]
Colour change:
Copper carbon [CuCO3] – Green – to Copper [III] oxide [CuO] – Black
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संबंधित प्रश्न
Methyl orange is used as an indicator. It shows colour change in acid, base and neutral substance. Tabulate your result as follows:
| Indicator | Colour change | Inference |
| Methyl Orange | No change | ...................... |
| .................... | Acid | |
| Yellow | ....................... |
Write the balanced chemical equation for the following reaction.
\[\ce{Aluminium + Copper chloride -> Aluminium chloride + Copper}\]
How will you indicate the following effect in a chemical equation?
A solution made in water.
Balance the following equation:
\[\ce{H2O2 -> H2O + O2}\]
Aluminium hydroxide reacts with sulphuric acid to form aluminium sulphate and water. Write a balanced equation for this reaction.
Name the type of chemical reaction shown by the following equation:
2Mg+ O2 → 2MgO
Balance the following simple equation:
NaHCO3 + H2SO4 → Na2SO4 + H2O + CO2
Match the columns.
| Reactants | Products | Types of chemical reaction | ||
| 1. | MgH2 | → | Mg + H2 | Endothermic |
| 2. | 2H2S + SO2 | → | 3S + 2H2O | Oxidation |
| 3. | CaO + H2O | → | Ca(OH)2 + heat | Exothermic |
| Redox | ||||
Which of the following is not a physical change?
Which of the following statements about the given reaction are correct?
`3"Fe"("s") + 4"H"_2"O"("g") -> "Fe"_3"O"_4("s") + 4"H"_2("g")`
- Iron metal is getting oxidised
- Water is getting reduced
- Water is acting as reducing agent
- Water is acting as oxidising agent
