chem mcq...

[ambitious1]

This autocatalytic reaction proceeds slowly at the start because there is little catalyst present, the rate of reaction increases progressively as the reaction proceeds as the amount of catalyst increases and then it again slows down as the reactant concentration decreases, not the product concentration.
Yes, it's C!

 

[alisha]

wont the line just go straight? if the reactant conc decrased?

 

[Feelguud77]

No.....catalyst and reactants are still present, the reaction has not ended................reactant concentration is now the limiting factor.

 

[ambitious1]

That'll only happen if the graph plotted was of the concentration of reactants against time, not the rate of reaction against time.
Understood? =)

 

[sweetiepie]

i hav a confusion in m/j 2006 q.9 ,12,14...

 

[xHazeMx]

i hav a confusion in m/j 2006 q.9 ,12,14....

Q9 is C

 

[sweetiepie]

how can u jux explain me plzz.... :%)

 

[xHazeMx]

how can u jux explain me plzz.....!!!

the total oxidtion number shouold be 0. O has oxidation number -2 and H has oxidation number +1. u have two O atoms so ( 2 x -2 = -4 ), H atom has +1 . hence, ( x - 4 +1 = 0 ) , X will be +3 ..

the same procedure with Ni(OH)2 will give u (x = +2)
try it

 

[sweetiepie]

no m not getting it i tried can u explain me plzzz n others also...

 

[xHazeMx]

no m not getting it i tried can u explain me plzzz n others also...

Ni(OH)2
O is -2 and H is +1 ( -2+1 = -1 ) and then u have (2) outside the bracket so ( -1 x 2 = -2 ) now the total oxidation number should be 0 so ( X - 2 = 0 , X = 2 )
hope everything is clear now

 

[rahultaneja2010]

Winter 2002 is a very tricky paper ..... Can someone help answer the tough questions in it ...? Good practise for everyone

 

[sweetiepie]

@ xHazeMx thanks alot wat abt 12 and 14 ....????

 

[xHazeMx]

@ xHazeMx thanks alot wat abt 12 and 14 ....????

for Q12, always put in ur mind that as temperature increases, the curve is shifted to right and downwards now read the question once again and u will find that it's simple
for Q14, it's D because the PCl5 and phosphorus hydroxide gives the same result with litmus paper

 

[sweetiepie]

oh yeahh it was simple uff i was jux making it to hard....

 

[xHazeMx]

oh yeahh it was simple uff i was jux making it to hard....

ALWAYS take everything easy :good:

 

[sweetiepie]

hmm okay..

 

[Hateexams93]

18 A solid nitrate fertiliser reacts with an alkali to produce a gas which turns damp pH paper blue.
What is the empirical formula of this fertiliser?
A NO3 B NHO3 C NH2O D N2H4O3
Can some1 plz explain why its D?????????

 

[deatheader]

I think first and second option is correct...

 

[Hateexams93]

no its D, but i don't know why :%)

 

[MHHaider707]

Answer is D!!!

Ammonium compounds produce Ammonia gas on reaction with alkali which turns red damp litmus blue and as D option is an ammonium compound so answer is D!!!