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प्रश्न
Fill in the blank.
Melting of ice is a _______ change.
उत्तर
Melting of ice is a physical change.
APPEARS IN
संबंधित प्रश्न
How do the following help in bringing about a chemical change?
heat.
Give reason.
Acidic soil is treated with quick lime.
TRUE \ FALSE
The evolution of a gas during a chemical reaction is shown by an arrow pointing downwards. True or false ?
TRUE \ FALSE
Positively charged electrode is called the anode. True or false ?
What are biocatalysts ?
Is kerosene an electrolyte or a non-electrolyte ?
How is a strong electrolyte different from a weak electrolyte?
Fill in the blank
A change in which the substance can be brought back to its original state is called a _______ change.
Explain the following reaction with one suitable example of Combination reactions .
Name the type of chemical reaction shown by the following equation:
CaCO3 → CaO + CO2
Name the type of chemical reaction shown by the following equation:
NaOH + HCl → NaCl + H2O
Explain by writing a word equation.
Hard water gets softened on mixing with a solution of washing soda.
Show with the help of diagram of electronic configuration how the following compound is formed from the constituent atoms.
Hydrogen chloride
What do you understand by 'chemical reaction'?
Give an example of the following chemical changes.
A reaction involving
(i) Change of state
(ii) formation of precipitate
Complete the following table and write your observations.
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Hydrogen sulphide |
Ammonia |
Sulphur dioxide |
Hydrogen chloride |
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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 |
What do you observe when Cl2 is passed through potassium iodide (KI) solution.
Write your observation and a balanced equation in the case of the following substances being heated.
Ammonium dichromate.
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc nitrate to nitrogen dioxide
State the following reaction represent oxidation or reduction.
\[\ce{Al->Al+++}\]
Give a balanced equation for a reaction involving the evolution of gas on the addition of dilute acid to calcium carbonate.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Lead nitrate.
What is the role of a catalyst in a chemical reaction?
The water we drink is a combination of hydrogen and oxygen.
What is the use of indicator?
Which of the following are chemical changes?
(i) Decaying of wood
(ii) Burning of wood
(iii) Sawing of wood
(iv) Hammering of a nail into a piece of wood
Two chemical species X and Y combine together to form a product P which contains both X and Y
\[\ce{X + Y -> P}\]
X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following concerning the species X, Y and P are correct?
(i) P is a compound
(ii) X and Y are compounds
(iii) X and Y are elements
(iv) P has a fixed composition
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Do you think the formation of rust from iron is a chemical change?
Explain how the painting of an iron gate prevents it from rusting.
______ is the chemical name of slaked lime.
