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Biology; Chemistry; Physics: Post your doubts here!

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exactly my point. it moves towards the anode but isnt produced!
well was just going through the past posts and wanted to correct you. The brown color is due to the bromine ion being oxidised to bromine. The bromine ion does not have a color, so the brown is due to the bromine molecules produced after oxidation :)
 
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Please help me with the following mcqs...
for the MCQ 4 my guess is C because the aluminium is most reactive of all requires more energy sorry if i am wrong
also by thinking that aluminium has the highest oxidation value reqiuring more electrons so more electricity
 
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This too please
its B because the sulphate ions CAN NEVER be discharged so always oxygen will be produced at the positive electrode.
its A as copper always discharges while there is a possibilty tht electrodes are of copper so anode will dissolve and oxygen will not be produce
 
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This too please
I've heard that even teachers aren't sure what the answer is to this one. I'll go with A because we have to note "ALWAYS TAKES PLACE" which means that we might even be using Copper electrodes. In every case, copper is deposited. For some reason, no one seems to bother thinking about the copper electrodes where the anode dissolves.
 
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3 In a titration between an acid (in the burette) and an alkali, you may need to re-use the same
titration flask.
Which is the best procedure for rinsing the flask?
A Rinse with distilled water and then with the alkali.
B Rinse with tap water and then with distilled water.
C Rinse with tap water and then with the acid.
D Rinse with the alkali.
Plz someone help me wd dis mcq.
 
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Plz someone help me wd dis mcq.
The answer is B. In the question, it is specified that we have to reuse the same titration flask, but the next reaction for which we have to reuse the flask has not been mentioned. For this, we rinse with tap water and then with distilled water.
If WE HAD TO DO THE SAME REACTION BETWEEN THE SAME ALKALI AND ACID SPECIFIED IN THE QUESTION AGAIN, THEN THE ANS WOULD HAVE BEEN C: RINSE WITH TAP WATER THEN WITH ACID.
These are facts, so learn em up.
 
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AView attachment 27143Any body help me with this question. With explanation please! :p
HCl breaks up into ions in aqueous solution so it conducts electricity only in aqueous solution. So, HCl is X.
We know that except graphite, non-metals don't conduct in any state so Sulphur (S) is W.
Metals can conduct in both solid state and molten state because of free electrons so Pb is Y.
Ionic compounds only conduct in molten form or aqueous solution because of free ions. NaCl is Z.
Summing it all up, the answer is C.
If you want a shorter method, just look at the options, Pb (the only one which conducts as solid and molten) is only in option C.
 
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Can sum1 xplain everything about double displacement reactions? :cry:
we do these reactions to make insoluble salts. If we need to make an insoluble salt, we will need to have two soluble salts, one with the cation of the required salt and the other with the anion of the required salt. E-g lets say we need to make Silver Chloride, an insoluble salt. We will need two soluble salts to prepare this, one with the cation Silver and the other with the anion Chloride. They must both be soluble too. So, I'll take Silver Nitrate, and the other soluble salt, NaCl. They both need to be soluble. Putting them in water would result in the following reaction

NaCl+ AgNO3 = AgCl + NaNO3

This reaction is an example of double displacement. The reason that Na displaced Ag from its nitrate is, because Na is more reactive than Ag, and looks for an anion which is more stable than Cl. (Cl is quite reactive so it is not as stable as NO3) Therefore, it bonds with NO3, displacing Ag in the process. Ag, then combines with the other anion, that is Cl, and this is how it works...........Do correct me anyone if i am wrong :)
 
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What do they form? Does copper react with them?what about caesium? What do they form?
Copper doesn't react at all with water neither does silver.
The first three form hydroxides which are soluble (calcium hydroxide is only slightly soluble).
The rest form oxides which are insoluble (e.g. MgO, ZnO, Fe2O3).
 
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