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प्रश्न
A metal nitrate 'A' on heating gives a metal oxide along with evolution of a brown coloured gas 'B' and a colourless gas, which helps in burning. Aqueous solution of 'A' when reacted with potassium iodide forms a yellow precipitate.
- Identify 'A' and 'B'
- Name the types of the reactions involved in the above statement.
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उत्तर
The metal in compound A is lead (Pb).
Therefore, we can write
Reaction 1 as
\[\ce{2Pb(NO_3)_2->[\Delta] 2PbO + 4NO_2 + O_2}\]
Reaction 2:
\[\ce{Pb(NO_3)_2 + 2KI ->Pbl_2 + 2KNO_3}\]
Compound A - lead nitrate: \[\ce{Pb(NO_3)_2}\]
Compound B - nitrogen dioxide- NO2
Reaction 1 is thermal decomposition, whereas,
reaction 2 is double decomposition reaction.
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संबंधित प्रश्न
Why is the amount of gas collected in one of the test tubes in the following Activity double of the amount collected in the other? Name this gas.
- Take a plastic mug. Drill two holes at its base and fit rubber stoppers in these holes. Insert carbon electrodes in these rubber stoppers as shown in the following Fig.
- Connect these electrodes to a 6 volt battery.
- Fill the mug with water such that the electrodes are immersed. Add a few drops of dilute sulphuric acid to the water.
- Take two test tubes filled with water and invert them over the two carbon electrodes.
- Switch on the current and leave the apparatus undisturbed for some time.
- You will observe the formation of bubbles at both the electrodes. These bubbles displace water in the test tubes.
- Is the volume of the gas collected the same in both the test tubes?
• Once the test tubes are filled with the respective gases, remove them carefully. - Test these gases one by one by bringing a burning candle close to the mouth of the test tubes.
Caution: This step must be performed carefully by the teacher.
- What happens in each case?
- Which gas is present in each test tube?

Give one example of a decomposition reaction which is carried out by applying heat.
What type of reaction is represented by the following equation?
2 FeSO4 → Fe2 O3 + SO2 + SO3
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State the change in colour observed in following case mentioning the reason:
Silver chloride is exposed to sunlight.
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\[\ce{Zn_{(s)} + H2SO4 -> ZnSO4_{(s)} + H2_{(g)}}\]
What does one mean by endothermic reaction? Give example.
Identify the type of following reaction :

Study the following figure and answer questions.

a) After heating Calcium carbonate, which gas is formed in a test tube?
b) When we pass this gas through limewater what change, did you observe?
c) Write down the chemical reaction showing the product formation after heating the Calcium carbonate.
Explain the reaction given in the figure.

