IIT-JEE problems

[Jaskanwar Singh]

sorry i forgot thanks.

 

[nims11]

@ nims

Nice method. Yes it is different from reduced mass concept.

Do you know the reduced mass concept too ?

The physics teacher at FIITJEE taught us but he wasnt open about it completely and asked us not to use it. So its not clear to me and i dont use it. Is it really useful?

 

[Jaskanwar Singh]

Explain me why is there excess pressure inside a bubble?

 

[pauldmps]

^^ To balance the contraction due to surface tension.

 

[Jaskanwar Singh]

ok thanks paul. my physics exam on Tuesday and the last

 

[abhijangda]

I am an ex-FIITJEEian and really I love all the teachers. They were really good.

Also answer to my question is:

(1 - m^2)x + my = am + b(1 + m^2)

 

[nims11]

Also answer to my question is:

(1 - m^2)x + my = am + b(1 + m^2)

hmm.. my answer was the same except for a '-' before 'am', looks like a minor mistake...

@all
i have a doubt, why cant sodium ethoxide be formed by reaction between ethanol and aq. NaOH?

 

[pauldmps]

^^ aq. NaOH is a strong base. As you might know that strong bases tend to follow elimination pathway. Hence elimination product ethene is formed

 

[abhijangda]

Let us do some Qualitative Analysis

Q. A scarlet compound (A) is treated with conc. HNO3 to giva a chocolate brown precipitate (B). The precipitate is filtered and the filtrate is neutralised with NaOH. Addition of KI to the resulting solution gives a yellow precipitate (C). The precipitate (B) on warming with conc. HNO3 in the presence of Mn(NO3)2 produces a pink coloured solution due to the formation of (D). Identify (A), (B), (C) and (D).

And let me know how many of you have done Inorganic Chemisty??

 

[pauldmps]

^^ Options please

 

[skeletor]

Let us do some Qualitative Analysis

Q. A scarlet compound (A) is treated with conc. HNO3 to giva a chocolate brown precipitate (B). The precipitate is filtered and the filtrate is neutralised with NaOH. Addition of KI to the resulting solution gives a yellow precipitate (C). The precipitate (B) on warming with conc. HNO3 in the presence of Mn(NO3)2 produces a pink coloured solution due to the formation of (D). Identify (A), (B), (C) and (D).

And let me know how many of you have done Inorganic Chemisty??

A = Lead tetraoxide
B = Lead dioxide
C = Lead iodide
D = Permanganic acid

 

[abhijangda]

^^ Options please

Sorry no options. I will post subjective questions only. no objective question

and ico absolutely right

 

[nims11]

i had my FIITJEE AITS today. Physics was DAMN TOUGH, questions were not suitable for objective type

 

[pauldmps]

I too had a practice test today. Same issue. Prerna Classes asks so long answer type questions in physics.

 

[abhijangda]

i had my FIITJEE AITS today. Physics was DAMN TOUGH, questions were not suitable for objective type

yes I got to know about AITS Full Test yesterday. It was tough. Thats the FIITJEE AITS which is very very tough as compared to JEE. Also you will find their GRAND MASTER PACKAGE and RANKER'S TEST PAPER FILE difficult.
did u gave FTSE??

 

[nims11]

yeah, but i gave it very casually and screwed up with it. i dont remember the rank but it was in 2K. does anyone know about the level of BMAT(brilliant's test series). some say its better than Fiitjee.

BTW here's a question from AITS,
a car has a 90Kwatt engine. What is the maximum speed that the car can attain if Resistance force on the car due to friction is directly proportional to velocity. i.e, F=k*v where k=100.
Do post the solution too.

 

[pauldmps]

Okay, I solved this:

Spoiler

Is max velocity = 30 m/s ?

This is how I did it:

Power = force x velocity (formula)
Friction = k x velocity (given)

P= Fv => F= P/v
fr = kv

When the car reaches its max. velocity, its accln. is zero => force by the engine = friction

F = fr
=> P/v = kv
=> v^2 = P/k
=> v = square root of (P/k)
=> v = sqrt. (90000/100) = 30 m/s

 

[Jaskanwar Singh]

nims is it like this -

Spoiler

let forward force by car be F. and frction be f.
-> F - f = ma.
max velocity is when acceleration becomes 0.
-> F = f = kv

P = Fv = kv^2 = 90000W
v^2 = 900
-> v = 30m/s

 

[Jaskanwar Singh]

paul our solutions match

 

[pauldmps]

Yep! The concept you applied is same too.

I guess if such questions are asked in the JEE, I'll surely qualify. Keeping my fingers crossed.

Now from my side, some questions from yesterday's test:

1. The Oxidation number of 'O' atom in HFO & HClO respectively are:

A. -1,0 B. 0,-2 C. -2,0 D. -2,+1


2. 0.04 g of an alcohol, R-OH was added to CH3MgBr & the gas evolved measured 11.2 ml at STP. What is the molecular mass of R-OH ? [Divide your answer by 10 to get an integer between 0-9]