Biology; Chemistry; Physics: Post your doubts here!

[SalmanPakRocks]

link?

 

[MuslimGirl]

can any 1 plz solve oct nov phy ppr 1 question 1 nd 6?? plzz

year?

 

[fatikhalid]

year?

oct nov

 

[Silent Hunter]

can any 1 plz solve oct nov phy ppr 1 question 1 nd 6?? plzz

Link please ?

 

[MuslimGirl]

oct nov

iz oct nov year????

 

[daredevil]

Ur book has nt described it fully that wat iz the reason behind it.....!!!

so can u tell the reason please bcuzi also don't know about it.... ^__^

 

[fatikhalid]

iz oct nov year????

yes

 

[fatikhalid]

link?

http://www.xtremepapers.com/community/threads/oct-nov-2011-papers.10997/page-2#post-142243 download da ppr 4m here

 

[snowbrood]

When something freezes bonds are made... When bonds are made energy is given out... Making it exothermic.... Or take it the other way, when it freezes, heat is given out and it cools down... Heat given = exothermic... Same goes for condensation...



Can you elaborate it a bit?

well buddy what do u want me to elaborate... have u studied fuel cell

 

[snowbrood]

maybe cuz exo means heat given out......... when heat given out... the inside temperature falls........ causes decrease in temperature.e.g. ice....... when it freezes.... an exothermic reaction occurs and it solidifies...... as heat is given out and temperature of ice falls.

( Anybody correct me if am wrong )

well its written in my book that the temperature of a exothermic reaction increases with time so how can u say that the temperature falls

 

[snowbrood]

heyy i think u need some correction here.... water is not a bad CONduCTOR. in fact it is an veryyyy gud cnductor of electricity. it lets current pass easily. it is a bad ELECTROLYTE. so there's a difference. the point is that water does conduct electricity but it does not DISSOCIATE and if we recall what we read in the book: an electrolyte is a substance that dissociates into its ions when electricity is passed through it and if from physics lessons we recall the definition of a conductor it is a thing which "lets current flow through it"; there is no mention of dissociation. hope that this helps... gud luk

agreed with you buddy

 

[fatikhalid]

A lamp, designed to work at 1.5 V, is connected to a cell of electromotive force (e.m.f.) 1.5 V. The
lamp lights at normal brightness.
The lamp is now connected to four similar cells, each of e.m.f. 1.5 V, arranged in parallel.
What is the effect of connecting the extra cells in this way?
A The lamp burns out.
B The lamp is dimmer.
C The lamp produces light for a longer time.
D The lamp produces light for a shorter time.

 

[Silent Hunter]

well its written in my book that the temperature of a exothermic reaction increases with time so how can u say that the temperature falls

but then how can you say that heat is given out? if heat is given out then the temp must get lowered... ?

 

[scouserlfc]

Can someone answer me this question. i always get confused in it.
Q- Why the amoeba living in fresh water have contractile vacuole, whereas the amoeba living in sea water do not have any contractile vacuole?

The fresh water ones have a contractile vacuole as in the fresh water the water outside the amoeba has high potential and that inside it has low potential so the water by osmosis has to go in amoeba but by putting more and more water in amoeba it will burst ! So to counteract this it has a contractile vacuole an adaption to its living place which helps to keep the excess water out by pressing against the water and not allowing it to enter it !
While those in sea water dont have it as sea water consists mostly of salts which makes the potential of water low and that inside amoeba high so water will leave amoeba by osmosis so the presence of a contractile vacuole reducing the amt of water inside amoeba is of no use,if its present it might not even allow Amoeba to have its normal water requirements !

 

[scouserlfc]

but then how can you say that heat is given out? if heat is given out then the temp must get lowered... ?

DUDES cmon !

Lets resolve this !

Exothermic think abt Exit which means to go out so in an exothermic reaction heat is given out to the surrounding causing the temp to increase in the surroundings ! bOND MAKING IS EXOTHERMIC !

Endothermic here think abt enter which means some one going in,now in a reaction which is endo heat is taken in by the reactants making the temp outside to fall ! Bond breaKIING IS ENDOTHERMIC

 

[snowbrood]

but then how can you say that heat is given out? if heat is given out then the temp must get lowered... ?

i gues then the book might have made a mistake buddy u dont kw how much this confused me man

 

[scouserlfc]

A lamp, designed to work at 1.5 V, is connected to a cell of electromotive force (e.m.f.) 1.5 V. The
lamp lights at normal brightness.
The lamp is now connected to four similar cells, each of e.m.f. 1.5 V, arranged in parallel.
What is the effect of connecting the extra cells in this way?
A The lamp burns out.
B The lamp is dimmer.
C The lamp produces light for a longer time.
D The lamp produces light for a shorter time.

is IT C !

 

[MuslimGirl]

can any 1 plz solve oct nov phy ppr 1 question 1 nd 6?? plzz

option C for ques 1 and A for question 6
correct me if i am wrong

 

[Silent Hunter]

DUDES cmon !

Lets resolve this !

Exothermic think abt Exit which means to go out so in an exothermic reaction heat is given out to the surrounding causing the temp to increase in the surroundings ! bOND MAKING IS EXOTHERMIC !

Endothermic here think abt enter which means some one going in,now in a reaction which is endo heat is taken in by the reactants making the temp outside to fall ! Bond breaKIING IS ENDOTHERMIC

CORRECT

 

[SalmanPakRocks]

A lamp, designed to work at 1.5 V, is connected to a cell of electromotive force (e.m.f.) 1.5 V. The
lamp lights at normal brightness.
The lamp is now connected to four similar cells, each of e.m.f. 1.5 V, arranged in parallel.
What is the effect of connecting the extra cells in this way?
A The lamp burns out.
B The lamp is dimmer.
C The lamp produces light for a longer time.
D The lamp produces light for a shorter time.

Is it C?