Read the text "my mother’s smile".
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the smile is a magic gift. it warms everybody without exception, cheers up, makes to feel happy. it is so pleasant to see a smiling person, especially, when your mum smiles. and my mum who is the dearest person in the world smiles so tenderly, sincerely and openly. it becomes lightly from her smile in the whole house. and so, you want to sing with joy!
my mummy is so beautiful when she smiles. and the crow`s-feet make her face so pretty!
when mummy smiles, i want to take her in my arms and whisper: "my dear mummy i love you very much" in such minutes of the happiness and mutual understanding she remembers the time when i was so small. she tells about the happy minutes of my birth. and there is nothing wonderful such minutes!
i think that for every child mummy is the best in the world, even when she is not so good and kind and always busy. coldness, inattention offend and wound children`s feelings most of all.
but nevertheless i am sure that every mum loves her child. it feels when being busy she finds a minute for the dialogue with her child and doesn`t forget to favour her child with the smile. such minutes are remembered for a long time, and sometimes for the whole life. that`s why it is pleasant to all children to see mum smiling and cheerful.
but it is important for us not only her smile, but also her understanding, love.
i would like all children in the world have mums and let they love their children and more often smile.
write true/false/doesn’t say:
1. the smile is a usual gift.
2. the writer is very intelligent and calm.
3. the author will go abroad without his mum.
M(Co2)=44 n=м/М=0,15
x 0,15
Caco3=Cao+co2
m(CaO)=8,4кг 1 1
n(caco3)=0,15 M(Caco3)=100 m(caco3)=
=100*0,15=15кг
V(CO2)=3,57м3
ро(СО2)=1,84кг/м3
Найти :
m(Caco3)-?
n(C6H6)=m/M=7.8/78=0.1 моль
n(Br2)=m/M=20/160=0.125 моль
n(HBr)=n(C6H6)=0.1 моль
m(HBr)=n*M=0.1*81=8.1 г
HBr+NaOH=NaBr+H2O
m(р-ра NaOH)=V*p=50*1.13=56.5 г
m(в-ва NaOH)=m(p-pa NaOH)*w=56.5*0.12=6.78 г
n(NaOH)=m/M=6.78/40=0.1695 моль
n(NaBr)=n(HBr)=n(H2O) = 0.1 Моль
В растворе останется избыток щелочи NaOH, соль NaBr:
m(NaOH)изб=n*M=(0,1695-0,1)*40=2,78 г
m(NaBr)=n*M=0.1*103=10.3 г
m(р-ра)=m(HBr)+m(p-pa NaOH)=8,1+56,5=64,6 г
Итого: w(NaOH)изб=m(в-ва)/m(р-ра)*100%=(2,78/64,6)*100%=4,3%
w(NaBr)=(10.3/64.6)*100%=15.94%≈16%