bits questions

hey lets start a thread for the prep of bitsat....will be posting in questions that might be of some relevence to the exam...

guys...plz post in ur questions

127 Answers

39
Pritish Chakraborty ·

cute cat your answer is wrong. It lacks one carbon.

11
SANDIPAN CHAKRABORTY ·

hmmm...got it...but in my post though a nasty 1...was it faulty???

39
Pritish Chakraborty ·

No sandipan..I should've given the options. I'm sure that answer is correct. Sorry :) It's just that it's not there in options...even I tried something similar.

1
cute_cat ·

What will this compound yeild on oxidative ozonolysis?

39
Pritish Chakraborty ·

The products are CHO-CH2-CHO and CHO-C(CH3)2-CHO.

1
cute_cat ·

@ pritish..yups that was wrong...jus a mistake....this is what is given as the ans.....can u plz explain???

Ph-CH=CHCH2Br

1
cute_cat ·

ans pritish ur ans for the ozonolysis is wrong....the products will be
OHOC-CH2-COOH and OHOC-C(CH3)2COOH....

it is oxidative workup....so ald will b converted to carboxylic acids....

1
cute_cat ·

nd somebody..plzz find a little time to explain these posts ...55,58,63

11
SANDIPAN CHAKRABORTY ·

Let (7+2√5)2n+1 = 72n+1(1 + (2/7)√5)2n+1 = I + f

now 72n+1(1 - (2/7)√5)2n+1 = f' (0 < f '< 1)

now I + f + f ' = 72n+1 . 2 (something....) = even integer...

now 0 < f < 1

and 0 < f' < 1

so 0 < f + f' < 2

so f + f' = 1

so I + 1 = even integer

so I = odd integer....

11
SANDIPAN CHAKRABORTY ·

Kp Kq qsn...

apply Kp=Kq(RT)∂ng

39
Pritish Chakraborty ·

Oh yeah..oxidative workup..sorry lol.
If that's the answer to your Ph-CH...etcetc question then I guess the only way to find out is to make resonating structures of the radical.

1
cute_cat ·

okay...so Kq means Kc

1
cute_cat ·

and pritish....can u do nake the resonating structures plzzz...

1
cute_cat ·

One mole of an adiabatic gas is allowed to expand reversibly and adiabatically from a temperature of 27C. The work done is 3 kJ. The final temperature of the gas is equal to [Cv = 20 kJ]....

i proceeded like.....dis was in chem...so dU= dW + dQ

then dU= dW

nCvΔT=-3000

20000(300 - T) = 3000

300 - T = 3/20

so T is approx 300 K

but the ans is 150 K

where m i wrong???

1
cute_cat ·

A planet of mass m moves around the sun of mass M in an elliptical orbit. The maximum and minimum distance of the planet from the sun are r1 and r2 respectively. The time period of thelanet is proportional to

a. r1^2/5

b. (r1 + r2)^3/2

c. (r1 - r2)^3/2

d. r^3/2

i don need ur ans alone..i need an explaination too

1
cute_cat ·

area of figure formed by ax±bx±c=0

1
cute_cat ·

n no1 solved that calculus prblm.......

1
1.618 ·

which calculus prob?

1
1.618 ·

For that gravitation problem...try using a famous property of ellipse Shall I name it?? :D
And...will sum of distance form both the focus ring some bell?

Try once again, else I'll post full solution.

1
1.618 ·

#107 shudn't be tuff. Did you make a graph and found intercepts?

1
rickde ·

for post #105...i think Cv value is wrong.......

1
cute_cat ·

@ ray

ya i got post num 107 and that gravitation one too....

thanks....[4]

and i was talking baout the post number 58......i got that derivative of teh given function is 0....but hw to find the value of the function itlsef???

1
1.618 ·

Hmm...doing.

1
Manmay kumar Mohanty ·

i marked something don't know if it is always valid or not
but

in that question (7+2√5)2n+1 that sandipan solved in post #100
2√5 = 4.472
and other is 7

we notice that 2√5 < 7
so we use f + f ' in the process as sandipan did

had it been ( 5√5 + 11 )2n+1 we use f - f ' in the process to find if integral part is even or odd


NOTE.
see i don't know if it is always valid but as far as i'm concerned jitne bhi question maine kiye hain unme ye valid hua hai

So this trick might help unless u know how to calculate square roots of numbers like 5 , 7 ,etc [1]

1
ayush_gupta ·

extemely sorry guys....... the ques was supposed to be
(4+2√5)2n+1. i solved this sum months ago i got it even but when sandi asked if it is always odd then i opened the book and copied from its explanation without seeing that all 4s in the explanation was misprinted as 7.
SORRY GUYS. EXTREMELY SORRY.

1
1.618 ·

Well, #58, the value is \frac{\pi }{4}

Let \phi (x)= k for all x

(here \phi (x) is the original function)

\Rightarrow \phi (\frac{\pi }{4})= k

\int_{0}^{\frac{1}{2}}{\sin^{-1} }\sqrt{x}dx+\int_{0}^{\frac{1}{2}}{\\cos^{-1} }\sqrt{x}dx=k

\int_{0}^{\frac{1}{2}}{\frac{\pi }{2}}dx=k

k=\frac{\pi }{4}

This gives,
\phi (x)=\frac{\pi }{4}

for all x.

39
Pritish Chakraborty ·

How did you assume that it's a constant function, Ray?
Ah I get it...the Leibnitz differentiation. Nicely done :)

1
cute_cat ·

me still nt getting........[2]

pi by four kahan se aya...apne ap se suppose kara kya....so that we can combine the two integrals???

39
Pritish Chakraborty ·

He used a convenient enough value...we can choose any because it's a constant function. It will give value "k" for all inputs, including pi/4.

1
cute_cat ·

okay..thanks ray and pritish....

one more doubt....

using a scalar triple product...we can find the volume of a tetrahedron and a parallelopiped....are there any other geometric interpretations???

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