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प्रश्न
Fill in the blank
A new substance is always formed in a _______ change.
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उत्तर
A new substance is always formed in a chemical change.
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संबंधित प्रश्न
The gas we use in the kitchen is called liquefied petroleum gas (LPG). In the cylinder, it exists as a liquid. When it comes out from the cylinder it becomes a gas (Change − A), then it burns (Change − B). The following statements pertain to these changes. Choose the correct one.
How do the following help in bringing about a chemical change?
pressure.
Define catalyst.
Complete and balance the following chemical equations:
`"H"_2"S"` + `"CI"_2` `→`
Fill in the blank:
The substances which undergo chemical change are called _______
Explain the following reaction with one suitable example of Double decomposition reaction.
Name the type of chemical reaction shown by the following equation:
Fe + CuSO4 → FeSO4 + Cu
Define the following term:
Precipitate
What is a chemical change? Give two examples of chemical change?
State the original colour of the following substance and colour of residue obtained after heating.
Lead nitrate
What do you observe when dilute sulphuric acid is added to the following:
Sodium Sulphide
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Thermal decomposition of mercury [II] oxide.
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
A coloured substance which leaves on strong heating a black residue and evolves two colourless gases one of which is acidic and the other neutral.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Copper nitrate.
Limestone contains ______ mainly.
Classify the following as physical or chemical properties
Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas.
Give an example of a chemical reaction for the following situation:
A change in colour is observed
______ is the chemical name of limestone.
What is the difference between reactants and products?
Collect information about the types of fuels used for cooking in your area. Discuss with your teachers/parents/others which fuels are less polluting and why.
