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Physics, Chemistry and Biology: Post your doubts here!

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Help with chemistry problem?
4.2 g of cerium reacted with oxygen to form 5.16 g of an oxide of cerium. Complete the following to determine the formula of this oxide.
(a) Number of moles of cerium atoms used
(b) Mass of oxygen that reacted
(c) Number of moles of oxygen atoms in oxide
(d) Ratio by moles of cerium atoms to oxygen atoms
(e) Formula of this oxide of cerium is ………
if the equation is given, then the problem could be solved easily. Is there any equation given of the reaction?
 
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Really mixed up with polymerisation ( polyester and polyamide ) . Do we need to learn the linkages , is the amide linkage c=o n-h ? how to apply it on pastpapers ?
How to remove the parts of the condensation polyester and polyamide ? What is a Diamene ? how can you draw tetrafluoroethene ? and the pastpapers on mole questions are very different than theory of moles. And are metals are reduced or oxidised, how can you find out which starts first. red or oxi ?
 
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The quality and quantity of food available worldwide has been improved by artificial
selection (selective breeding) and genetic engineering.
(d) Use a named example to outline how artificial selection is used to improve the quantity
or quality of food.
 
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T
Its quite easy u need to know the no of electrons needed/lost by each atom to become stable
P requires 2 electrons and Q needs to lose 1 electron
So P : Q
2 : 1
CROSS THEM OVER so the answer is PQ2
Thankx fr ur help :D
 
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hm guys..can someone please explain me the earthing thing related to induced spheres.
When do the electrons escape TO earth from sphere and when do they MOVE UP FROM earth to sphere?(Physics)
 
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Have you guys finish every subjects in your school?

Mine, Bio : Only inheritance and DNA left
Physics: Done everything
Chemistry: Polymers...
 
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Have you guys finish every subjects in your school?

Mine, Bio : Only inheritance and DNA left
Physics: Done everything
Chemistry: Polymers...
Maaaan...... i guess ur very late in our skool all the subjects have been completed +revision twice :p
 
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