Sunday

April 20, 2014

April 20, 2014

Total # Posts: 22

**chemistry**

just take H2O AND CH3CH2OH as example.why say that h2o can form two hydrogen bond per molecule but CH3CH2OH only one.i am confused as both of them also has two lone pairs per molecule,is it true that one hydrogen atom will result in only one hydrogen bond and two hydrogen bond...

**Physics**

that means move towards or backward the object?

**Physics**

suppose the camera has only one len .if i want to take a sharp image of a distant object,how should the len move,forward or backward.how about if nearby object?

**math**

let x be one of the part of the string and represent ratio 3,that mean 40-2x represent ration 2 x/(40-2x)=3/2 x=15 that mean the string can be divide into 15cm, 10cm and 15cm

**geometry**

a^2+b^2=c^2 a,b & c are sides of a triangle note: a+b>c a+c>b b+c>a

**math problem**

7(41-5Y) +8Y =44 SOLVE Y AND THEN PUT Y = ? IN X=41-5Y THEN SOLVE X in fact ,purpose of substitution is to make a equation have only one unknown so that we can easily solve the problem

**physics**

insufficient information,cant ans it

**physics**

in fact,there are many different affect on the gas particles when heating the gas due to different condition.this is taught in a topic of gas law and kinetic theory.but simply saying,when heating a gas,the average KE OF GAS PARTICLES increase,then the average speed of each par...

**chemistry(balance equation)**

S + H2SO4 ----> SO2 +H2O

**chemistry(balance equation)**

thank you very much,your teaching really makes me a good start. then how about balance S +H2SO4 ---> SO2 +H2O ??

**chemistry(balance equation)**

Thank you DrBob, but i am only a form 4 student in hk,i havent learnt about anything of redox.is there any SUPER SHORT CUT for balance simple and complex equation?in fact i have asked several people,some of them said that take LCM of the atom counts,but i dont know take which ...

**Algebra**

1/6d + 13 = 20 1/6d =20-13 d/6 =7 d = 7*6 d = 42 3/5(s-8)=9 [3(s-8)]/5=9 3(s-8)=9*5 s-8 = 45/3 s =15 +8 s=23 the next one you try it

**pennfoster**

ans is b. helped is a verb with past tense

**maths**

FIRST,look for the unit L----Litre leak?L per minute-------L m^-1 that mean L/ L m^-1 =1/ m^-1 =m therefore, ans: 20/(2/3) =30minutes.

**geometry**

your question is actually unclear.i think your question lack some criterias.for example,which two lines are equal.just take the numbers u give,BA=BC,then 4y+6=6y-3,then its easy to find y

**physics**

its just a simple ratio problem solution: 100A X A 0.01 THEN THE EQUATION WILL BE 100A/A=X/0.01

**chemistry**

concentrated H2SO4(l)(18M)contain 98% H2SO4 by mass,how about the 2 %,is it water?

**Physics**

when temp increase,that mean average KE increase,if state change from solid to liquid or liquid to solid ,potential energy increase For IDEAL GAS,it wont change to any state under HIGH TEMP LOW PRESSURE,so average KE increase but potential energy remains unchange as far as we ...

**chemistry**

2NH3 + 3Cuo -----> 3Cu + 3H2O +N2

**Chemistry Balancing Equations**

i have just learnt a little about balancing equation but i hope i can help your coefficient only: question 1 , 4,7 no need to balance 3)2,1,2 6)only HCL had a mole ratio of 2 the other i dont know,sorry

**chemistry**

aluminium is excess. let x be the maximum mass of AlCl3 (x/133.5)/(35/71)=2/3 x= (find x by yourself)

**science**

it is a compound.because it exists more than one element and also this two element has change of their no of electrons.that means sodium HAS REACTED with chlorine and changed to a product. OF course,sodium chloride can dissolve in water,and we call this a sodium chloride solut...

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