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Physics, Chemistry and Biology: Post your doubts here!

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Describe the action of heat ( if any) on :

1) Hydroxides of Ca, Cu, Fe, Mg, K, Na, Zn
2) Nitrates of Ca, Cu, Fe, Mg, K, Na, Zn


Awesome12 eureka!
Hydroxides:
•KOH, NaOH UNchanged.
•The rest: hydroxide + heat ---> oxide + water
e.g. Ca(OH)^2 ∆---> CaO + H2O;
2Fe(OH)3 ∆---> Fe2O3 + 3H2O

Nitrates:
•NaNO3, KNO3: nitrate + heat ---> nitrite + oxygen
e.g. 2NaNO3 ∆---> 2NaNO2 + O2
•The rest: nitrate + heat ---> oxide + nitride + oxygen
e.g. 2Ca(NO3)2 ∆---> 2CaO + 4NO2 +O2
2Fe(NO3)2 ∆---> 2FeO + 4NO2 + O2
 
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how is it C shdnt it b A View attachment 42765
From the diagram, it appears that the metal case does not go back to the beginning so that means current wouldn't flow after it reaches the cable so its not a full circuit. Ofcourse, u can argue otherwise however u must remember that CIE is looking for the "most suitable answer" so the most plausible answer in those options is that someone will receive a shock because as soon as he touches it, the circuit is complete.
 
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Why does acidified KMnO4 turn colorless in alkenes?
Because KMnO4 is a good oxidizing agent. It's not your average good oxidizing agent, but a super one. It breaks the double bond present in alkenes, which allows them to form more bonds with other elements. The oxygen molecules from KMnO4, since there are a total of 4, they move on to the alkene, and 2 are added to either side.
Now, KMnO4 has no more oxygen molecules left. Due to this, it loses its prominent purple color.
The mechanisms of this reaction is really complex and not present in our level, but this is the general idea.
 
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A very simple question from me... What is the difference between evaporation and crystallisation... What does one method offer that the other does not? I'm posing this question because both methods of separation seem to satisfy the same objective: extracting a dissolved substance from a solution...
we evaporate to remove the liquid completely which would form anhydrous crystals, while in crystallisation we don't remove the water r crystallisation nd obtain hydrated crystals..... :)
 
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