Biology; Chemistry; Physics: Post your doubts here!

[smiling star]

This also

 

[darkvoid]

Can someone help me out with these chemistry Mcqs? darkvoid or Error Syntax ?View attachment 60123 View attachment 60123 View attachment 60123

MCQ 24: B
In part A silver chloride will form (insoluble so precipitate will form)
In part C lead(II) chloride again is insoluble
In part D silver chloride forms again.
In part B sodium chloride forms which is soluble so no ppt.

MCQ 29: C
Desalination removes salt from seawater, salt is soluble. Filtration obviously is used for insoluble substances, and distillation evaporates and condenses the water separating the impurities from the water.

MCQ 16: D
There are two conditions for the bulb to light. Firstly the electrolyte must be liquid or molten and cannot be an organic compound as they do not conduct electricity (C2H5OH). Option B and and C are therefore wrong. Secondly the electrodes must be made of metals having different reactivities. The greater the difference in reactivity the brighter the bulb lights. So D is correct since the metals used are Cu and Ag. Cu is slightly more reactive than Ag. So Cu will lose electrons faster than Ag causing electrons to flow and electricity to be produced.

Hope this helped, if you have any more questions feel free to post

 

[smiling star]

MCQ 24: B
In part A silver chloride will form (insoluble so precipitate will form)
In part C lead(II) chloride again is insoluble
In part D silver chloride forms again.
In part B sodium chloride forms which is soluble so no ppt.

MCQ 29: C
Desalination removes salt from seawater, salt is soluble. Filtration obviously is used for insoluble substances, and distillation evaporates and condenses the water separating the impurities from the water.

MCQ 16: D
There are two conditions for the bulb to light. Firstly the electrolyte must be liquid or molten and cannot be an organic compound as they do not conduct electricity (C2H5OH). Option B and and C are therefore wrong. Secondly the electrodes must be made of metals having different reactivities. The greater the difference in reactivity the brighter the bulb lights. So D is correct since the metals used are Cu and Ag. Cu is slightly more reactive than Ag. So Cu will lose electrons faster than Ag causing electrons to flow and electricity to be produced.

Hope this helped, if you have any more questions feel free to post

Thankyouu so much
Can you reed plain mcq 29?
Also, I wanted to know how many years of p2 I should practise for chem max?

 

[darkvoid]

Thankyouu so much
Can you reed plain mcq 29?
Also, I wanted to know how many years of p2 I should practise for chem max?

MCQ 29 is C because:
Desalination is used to remove salt from seawater and salt is soluble. The question asks for insoluble substances.
Chlorination has nothing to do with impurities as it kills bacteria and makes the water hygienic.
Options A and B are therefore wrong.
Filtration separates water from insoluble substances such as sand , which remains on the filter paper as residue while the water passes through as the filtrate.
Distillation is normally used for separating soluble substances but can also be used for insoluble ones. The water simply evaporates , condenses and is collected separately while the impurity is left behind in the flask.

Do as many as possible , atleast from 2010 onwards.

 

[areeba240]

helppppp plzzzzzzzzzzz
thanks in advance

 

[areeba240]

helppppp plzzzzzzz
thanks in advance

 

[smiling star]

MCQ 29 is C because:
Desalination is used to remove salt from seawater and salt is soluble. The question asks for insoluble substances.
Chlorination has nothing to do with impurities as it kills bacteria and makes the water hygienic.
Options A and B are therefore wrong.
Filtration separates water from insoluble substances such as sand , which remains on the filter paper as residue while the water passes through as the filtrate.
Distillation is normally used for separating soluble substances but can also be used for insoluble ones. The water simply evaporates , condenses and is collected separately while the impurity is left behind in the flask.

Do as many as possible , atleast from 2010 onwards.

Oh thanks a lot
I know but I see that not much time is left and I haven't even started ATP yet so I'm thinking to cut back on a few years
I'll do from 2010 once I'm done with those will do Atps and I get time I'll do the remaining theories too

 

[darkvoid]

Oh thanks a lot
I know but I see that not much time is left and I haven't even started ATP yet so I'm thinking to cut back on a few years
I'll do from 2010 once I'm done with those will do Atps and I get time I'll do the remaining theories too

Yes, do Atps in the end , they are short and can be done fairly quickly.
Hope it all goes well for all of us.

 

[darkvoid]

View attachment 60164
View attachment 60165
helppppp plzzzzzzz
thanks in advance

I don't think this is O level's , you have posted in the wrong forums perhaps.

 

[smiling star]

I was practising this worksheet but I didn't understand part b (i and (ii?
The answer is written in red but can someone explain me this?

 

[smiling star]

Also, I mess up moles in every pastpaper I have practised so far so darkvoid or Error Syntax, can you people tell me any link or site or video or resource from where I can practise and improve this chapter? Thanks a lot
And are you guys done with all pastpapers of chemistry, bio, physics?

 

[bogus]

MCQ 29 is C because:
Desalination is used to remove salt from seawater and salt is soluble. The question asks for insoluble substances.
Chlorination has nothing to do with impurities as it kills bacteria and makes the water hygienic.
Options A and B are therefore wrong.
Filtration separates water from insoluble substances such as sand , which remains on the filter paper as residue while the water passes through as the filtrate.
Distillation is normally used for separating soluble substances but can also be used for insoluble ones. The water simply evaporates , condenses and is collected separately while the impurity is left behind in the flask.

Do as many as possible , atleast from 2010 onwards.

Just wanted to let you know that the answer to 29 is D
I also thought it would be C because distillation CAN possibly be used to remove insoluble substances but i think the question does not take that into regard.
Can the person who posted this question please recheck the answer? I know it seems quite confusing but this is the only conclusion that I can draw

 

[bogus]

View attachment 60163
helppppp plzzzzzzzzzzz
thanks in advance

Which board's paper is this? surely it's not GCE!

 

[bogus]

I was practising this worksheet but I didn't understand part b (i and (ii?
The answer is written in red but can someone explain me this?View attachment 60190

These answer's frankly speaking make no sense. Copper would not be used because it is below Hydrogen in the reactivity series and so it will not react with HCl, or any other acid for that matter.
The test wire should in my opinion (not too sure about this though) be dipped in an alkali to neutralise it before repeating the experiment.
Hope it helped!

 

[smiling star]

Just wanted to let you know that the answer to 29 is D
I also thought it would be C because distillation CAN possibly be used to remove insoluble substances but i think the question does not take that into regard.
Can the person who posted this question please recheck the answer? I know it seems quite confusing but this is the only conclusion that I can draw

The answer is actually C even i thought it was C at first

 

[Error Syntax]

Also, I mess up moles in every pastpaper I have practised so far so darkvoid or Error Syntax, can you people tell me any link or site or video or resource from where I can practise and improve this chapter? Thanks a lot
And are you guys done with all pastpapers of chemistry, bio, physics?

I have great video of Moles will upload them for you in youtube. It talks about everything of moles from GCSEs althougth the guy teaching is american and Sorry I couldnt answer the question was away for a while.

 

[Error Syntax]

Also, I mess up moles in every pastpaper I have practised so far so darkvoid or Error Syntax, can you people tell me any link or site or video or resource from where I can practise and improve this chapter? Thanks a lot
And are you guys done with all pastpapers of chemistry, bio, physics?

tp://www.dailymotion.com/video/k2pUErCBrs6AFh8PTKB here is a private link its about most of the moles question. Uploading more.

 

[smiling star]

I have great video of Moles will upload them for you in youtube. It talks about everything of moles from GCSEs althougth the guy teaching is american and Sorry I couldnt answer the question was away for a while.

tp://www.dailymotion.com/video/k2pUErCBrs6AFh8PTKB here is a private link its about most of the moles question. Uploading more.

Haha its alright, thanks for this video :') I couldnt find any resource myself and moles is a difficult chapter..

 

[Error Syntax]

Haha its alright, thanks for this video :') I couldnt find any resource myself and moles is a difficult chapter..

Its easy dude just relax and do the questions. here is the other video dude

 

[smiling star]

Its easy dude just relax and do the questions. here is the other video dude

Post the link of the other video
it wont playy