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Chemistry: Post your doubts here!

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Ans is c but why..
I'm not that good in chemistry, but from my understanding it cant be a,b, or d because these three properties are also present in NaCl and MgO and the question says that CsCl has a different structure than these two, so the only distinct property that CsCl has is the radii ratio.
 
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I'm not that good in chemistry, but from my understanding it cant be a,b, or d because these three properties are also present in NaCl and MgO and the question says that CsCl has a different structure than these two, so the only distinct property that CsCl has is the radii ratio.
Let me know if this helped.
 
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One mole of sulfuric acid is used to make an aqueous solution. The solution contains H2SO4
molecules, H+ ions, SO4 2– ions and HSO4– ions.
Which statements are correct?
1 The solution contains 6.02 × 1023 sulfur atoms.
2 The solution contains an exactly equal number of H+ ions and HSO4– ions.
3 One mole of SO4 2– ions contains two moles of electrons.
answer is D means only option 1 is correct. plz justify
 
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Hello fellow students, if you or someone else you know are preparing for O-Level or A-Level chemistry this October/November 2020, or sometime in the future, please check out my YouTube channel where I feature step-by-step tutorial videos on my thought processes in addressing the examination papers across the different variants of the Cambridge International curriculum.


Even if your zone(s) is/are set to sit for a specific variant, it never hurts to check out the same curriculum in other variants for practice. Please subscribe to the channel to support this not-for-profit endeavour. Also, please spread the words to your friends/teachers/contacts to benefit more students like yourself.

Thanks.
 
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First write the balanced equation.
2H2S + 3O2 ------> 2H2o + 2SO2
(Note:For AS you're not required to know this equation by heart but whenever such a question appears, there are either hints in it about the products or the products are stated explicitly. Nonetheless, you're expected to know the oxidation/combustion products of H2 and S2. )
Moles of H2S = Mass/Molar Mass = 8.65/((32.1 + 2) = 173/682
Moles of O2 = (3 x (173/682))/2 (since mole ratio H2S:O2 = 2:3 from the equation) = 519/1364
Volume = moles x 24 = (519/1364) x 24 = 9.13 dm^3
 
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Hi all, I have added more short tutorial videos covering specific concepts, like quick-bites with worked examples, explaining step-by-step how to proceed with calculations/explanations. These complement the longer videos that cover full past paper tutorials.


My videos/YouTube channel try to achieve more than just solving a paper or following mark scheme. Some have found some mistakes within, which is good. The viewers are learning! I don't usually try to correlate to mark schemes, and hey mistakes are common, but I try to minimise mine of course.

If you like my teaching style/explanations, please subscribe to the channel. Do drop comments if there are areas you wish me to cover. Learning chemistry is more than just about acing the exams. If you understand the story behind the concepts, then you will get the grades naturally.
 
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Hi all, I have added more short tutorial videos covering specific concepts, like quick-bites with worked examples, explaining step-by-step how to proceed with calculations/explanations. These complement the longer videos that cover full past paper tutorials.


My videos/YouTube channel try to achieve more than just solving a paper or following mark scheme. Some have found some mistakes within, which is good. The viewers are learning! I don't usually try to correlate to mark schemes, and hey mistakes are common, but I try to minimise mine of course.

If you like my teaching style/explanations, please subscribe to the channel. Do drop comments if there are areas you wish me to cover. Learning chemistry is more than just about acing the exams. If you understand the story behind the concepts, then you will get the grades naturally.
 
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the strongest bond to break will require the highest energy to break, and thus will linger around for the longest. That should help you from the chemistry point of view, though biologists would have learnt to compare their strength also. Ionic bonds in general are stronger than disulphide bonds.

If anyone need A Level chemistry help, consider subscribing to my YouTube channel, as linked in the post above.
 
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Bu
the strongest bond to break will require the highest energy to break, and thus will linger around for the longest. That should help you from the chemistry point of view, though biologists would have learnt to compare their strength also. Ionic bonds in general are stronger than disulphide bonds.

If anyone need A Level chemistry help, consider subscribing to my YouTube channel, as linked in the post above.
but the answer is A , how?
 
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Bu

but the answer is A , how?
I guess the covalent S-S bond is indeed stronger than the zwitterionic interactions. I mean in chemistry, when you have to break covalent bond in the sense of a giant molecular lattice network, that takes roughly the same or even larger amount of energy to break, i.e. to melt a giant ionic framework.

You must have covered this in biology classes specifically in terms of these bond strengths. I do stand corrected that the covalent S-S bond can indeed be on the same level as the zwitterionic interactions (which are obviously not as strong as a cationic metal and anionic metal interactions)..
 
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Hi all, I have added more short tutorial videos covering specific concepts, like quick-bites with worked examples, explaining step-by-step how to proceed with calculations/explanations. These complement the longer videos that cover full past paper tutorials.


My videos/YouTube channel try to achieve more than just solving a paper or following mark scheme. Some have found some mistakes within, which is good. The viewers are learning! I don't usually try to correlate to mark schemes, and hey mistakes are common, but I try to minimise mine of course.

If you like my teaching style/explanations, please subscribe to the channel. Do drop comments if there are areas you wish me to cover. Learning chemistry is more than just about acing the exams. If you understand the story behind the concepts, then you will get the grades naturally.
Can you help with this please?
 

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Help please!!!

Well you should always have tried something, i.e. outline your ideas then people can just help to guide you along. Remember, if you don't do that and just rely on someone explaining from zero, you risk losing it all big time in the real exam. By then it becomes too late.

Go for option 2 => since these involve specific isotopes, they both have mass of 34. Even if you remove some of the dioxygen, the average mass will remain the same.

Check number 1. Same deal with option 2. Average mass will just be 34 because all the molecules present have mass of 34.

Check number 3. H2S + 3/2 O2 --> SO2 + H2O (to balance the eqn - gcse/o level, no). I leave you to think about limiting and excess reactant based on the reacting mole ratio, and the information that you have equal number of these two molecules in the mixture. It all comes down is 3 correct or not.
 
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