physics and chemistry doubts!!

[gary221]

what is the best thing to write in ans for... why does the dust particles does not settle down in brownian motion ?

Because of continous collisions with the air particles, which are moving randomly. Continously.

 

[gary221]

330 m/s. Mistake.

Okay, first find the time taken by sound to travel the given distance via the steel rails.
So, Time = Dist/ Speed → 120/5000 = 0.024 s
Then the time taken to travel the same distance via air.
So, Time = 120/330 = 0.36 s

So, diff in time = 0.36 - 0.024 = 0.339 s.
Hope it's right....and that you get it.

 

[Faiza Anwar]

guys need an explanation 4 this question plz.
View attachment 43127

the ans ic C. coz the resistance of the bottom resistor is now more so the voltage drop over here is more (the voltage drop is always more around the resister with higher resistance).. i hope u get it..

 

[shadil.me]

can anyone explain 4 me this question.

 

[Faiza Anwar]

can anyone explain 4 me this question.
View attachment 43133

5 hrs- 1/2
10 hrs-1/4
15 hrs-1/8
20 hrs-1/16.... so as they are asking abt BEFORE so we will multiply the mass with 16. 0.48 x 16=7.68
tell me if u didn't understand any thing...

 

[Faiza Anwar]

can anyone explain 4 me this question.
View attachment 43133

nd if they ask for AFTER so we would divide by 16...

 

[shadil.me]

nd if they ask for AFTER so we would divide by 16...

thank u very much.

 

[Faiza Anwar]

how was the exam people ?

 

[Faiza Anwar]

thank u very much.

you are welcome ! how was your exam?

 

[Phoenix Blood]

how was the exam people ?

Okkies.

 

[dubi2pro]

anyone please?

 

[dubi2pro]

this as weellll

 

[Faiza Anwar]

anyone please?

the mass of one mole A5H2 is 377 ?

 

[dubi2pro]

the mass of one mole A5H2 is 377 ?

No :S

 

[Faiza Anwar]

No :S

al right i thougt 5 nd i was goig to say ur ans is wrong acc to that... lemme see if i can help u with the other parts..

 

[dubi2pro]

al right i thougt 5 nd i was goig to say ur ans is wrong acc to that... lemme see if i can help u with the other parts..

ah ok its AsH2

 

[Faiza Anwar]

anyone please?

mass of one mole of AsH2 is 77...
154-77=77
so it will be twice which is As2H4
nd from this u can draw the structure..
i hope u get it..

 

[shadil.me]

you are welcome ! how was your exam?

good.

 

[Faiza Anwar]

this as weellll

3 N-H bonds which are twice as mentioned in eq.
2x3=6
6x388= +2328
H-H is breaking so endo, nd N-H is forming so exo..
energy taken in for bond breaking is (944+1308=2252), while energy released in bond making is 2328..
energy released in bond making is more than energy taken in for bond breaking so forward reaction is exo..

 

[shadil.me]

good.

how was urs?