Biology; Chemistry; Physics: Post your doubts here!

[hellangel1]

how does a low density hydrogen cloud in space becomes a star?
please dont repeat the words of marking scheme..i need some detail

 

[falcon678]

how does a low density hydrogen cloud in space becomes a star?
please dont repeat the words of marking scheme..i need some detail

here's the details.!!!

 

[ashiqbal]

in a.c motor carbon brushs r not used...split ring commutator is used....in DC motor carbon brush is used to chnge diretion of current every half turn so tht coil rotates is same direction..!!!

carbon brushes are used both in AC generator and DC motor to keep contact with circuit without restricting movement!
in AC generator, SLIP rings are used
in DC motor, SPLIT ring commutator is used

 

[falcon678]

carbon brushes are used both in AC generator and DC motor to keep contact with circuit without restricting movement!
in AC generator, SLIP rings are used
in DC motor, SPLIT ring commutator is used

oohhh yeah...... i mixed em up....

 

[ashiqbal]

can anyone explain this
http://www.xtremepapers.com/papers/...l O Level/Chemistry (5070)/5070_s11_qp_42.pdf
why is Q6 answer not a?
because in P, the concentration is high, but surface area is low(zinc pieces)
an in Q, the concentration is low, and surface area is high(zinc powder)
wouldnt this account for same speed of reaction??

 

[luckywang]

in a.c motor carbon brushs r not used...split ring commutator is used....in DC motor carbon brush is used to chnge diretion of current every half turn so tht coil rotates is same direction..!!!

is the split-ring commutator function as reverse the current, not the carbon brush?

 

[SalmanPakRocks]

can anyone explain this
http://www.xtremepapers.com/papers/CIE/Cambridge International O Level/Chemistry (5070)/5070_s11_qp_42.pdf
why is Q6 answer not a?
because in P, the concentration is high, but surface area is low(zinc pieces)
an in Q, the concentration is low, and surface area is high(zinc powder)
wouldnt this account for same speed of reaction??

The answer would be d.
observe the molarity of both of the acid.

 

[ashiqbal]

The answer would be d.
observe the molarity of both of the acid.

that i know, but why P is faster when surface area of zinc is less?

 

[ashiqbal]

is the split-ring commutator function as reverse the current, not the carbon brush?

this has been cleared man:

carbon brushes are used both in AC generator and DC motor to keep contact with circuit without restricting movement!
in AC generator, SLIP rings are used
in DC motor, SPLIT ring commutator is used

 

[SalmanPakRocks]

that i know, but why P is faster when surface area of zinc is less?

But the amout of acid is low and the concentration is high. Second one is rather dilute one. So reaction would be fast at P

 

[luckywang]

can anyone explain this
http://www.xtremepapers.com/papers/CIE/Cambridge International O Level/Chemistry (5070)/5070_s11_qp_42.pdf
why is Q6 answer not a?
because in P, the concentration is high, but surface area is low(zinc pieces)
an in Q, the concentration is low, and surface area is high(zinc powder)
wouldnt this account for same speed of reaction??

answer is C?

 

[falcon678]

can anyone explain this
http://www.xtremepapers.com/papers/CIE/Cambridge International O Level/Chemistry (5070)/5070_s11_qp_42.pdf
why is Q6 answer not a?
because in P, the concentration is high, but surface area is low(zinc pieces)
an in Q, the concentration is low, and surface area is high(zinc powder)
wouldnt this account for same speed of reaction??

dude it cant be A becuz here HYDROGEN production is being talkd bout...in a) it is shwn tht is Q more hydrgn is producd wich is NOT the case as less concntratd acid is used here compard to P...so hydrogn gas producd in P wld be double of tht producd in Q.......so it wld be (c)

 

[falcon678]

answer is C?

yes it is (c)

 

[SalmanPakRocks]

Answer is D -_____-

 

[falcon678]

i

Answer is D -_____-

ohk yes it IS (d)

 

[asd]

Answer is D -_____-

yes it is (c)

It's D.
Production depends upon the moles. And the rate of reaction on the conc. of acid!!

 

[falcon678]

It's D.
Production depends upon the moles. And the rate of reaction on the conc. of acid!!

ohk dude i AGREE itz (d)..... -.-

 

[asd]

why are you guys preparing for chem, Bio will be first... No?

 

[SalmanPakRocks]

I don't have bio.

 

[ashiqbal]

But the amout of acid is low and the concentration is high. Second one is rather dilute one. So reaction would be fast at P

but yar wouldnt particle size also effect rate of reaction???