C2H4 + Br2==>C2H4Br2

metan(CH4) ko td với brom

b, mol hỗn hợp = 0.15(mol)

Do chỉ có etilen td được với brom nên khí thoát ra là metan 

==>mol Ch4=0.1(mol)==>molC2H4=0.05(mol)

%V CH4=66.67%==>%VC2H4=33.33(bài này dễ mà )

kết tủa trắng là 2,4,6 - tribromphenol==> mol kết tủa=19,86:331=0,06(mol)

C2H5OH + Na==> C2H5ONa + 1/2H2

C6H5OH + Na ==> C6H5ONa + 1/2H2

C6H5OH + 3Br2 ==> C6H2OHBr3(kết tủa trắng) + 3HBr

Gọi mol C2H5OH,C6H5OH lần lượt là a,b

Có mol H2=0,15(mol)=1/2a+1/2b

b=0.06(mol)

a=0,24(mol),b=0,06(mol)

==>molC2H5OH=0,24(mol),mol phenol=0,06(mol)

%m C2H5OH=66,18%,%m C6H5OH=33.82%

câu 1: N Ag=0,3(mol)

NAg:Nx=0,3:0,1=3(mol)>2==>hỗn hợp phải gồm anđehit fomic ct:HCHO và 1 anđehit no X kế tiếp ==>ctpt: C2H4O

Đề bài có cho kế tiếp không? 

ta tính được nco2=0,4(mol)

mol h2o=0,5(mol)

từ 2 điều trên , ta suy ra đây là ancol no , đơn chức , mạch hở nên mol ancol=0,5-0.4=0,1

ctct:CnH2n+1OH

n=mol CO2:mol ancol=0,4:0,1=4. Suy ra ctpt:C4H9OH

Enviroment is the most important thing for our life. Enviroment is the air we breath, the water we drink and is everything we need for our life. But now that most important thing for our life is being polluted and by many different ways. This pollution affects the health of living things. Air is damaged by car and lorry fumes, and power stations create acid rain which destroys entire forests and lakes. When fossil fuels i.e. oil, gas and coal are burned to provide energy for lighting, cooking etc. they form polluting gases. Not only on land but also in the sea, oils spills pollute sea water and kill marine life; chemical waste from factories and sewage works, and artificial fertilisers from farmland, pollute river water, killing wildlife and spreading disease. Everything is being caused by human’s existence. Humans create such a lot of rubbish! Each household produces about 1 tonne of rubbish every year! Most of this is taken away by dustmen and buried in enormous landfill sites or burned in incinerators - both of these actions can be dangerous for the environment. 
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 Keep clean environment isn’t only all ways are mentioned before but also to protect natural resources. That is the way to conserver wild life. First we need to conserve the old forest, rainforest, build more safari and national park, and plant more trees to make place to live for wild animals. Second we need to prohibit hunters who hunt animals too many out of the law allowance. 
Finally, we now know that enviroment is the most important thing for life and we know how to protect and use it scientifically. Everyday we invent and find more and more way to protect enviroment. I hope that in the future the earth will be cleaner.