1SOLVED 4.an unknown resistance X is to be determined using resistances R1,R2 or R3.their corresponding null points are A,B and C.which of the 3 will give the most accurate reading and why? [2005]
NEWLY ADDED QUESTIONS unsolved questions are underlined.
1.for what value of k the system of linear equations x+2y+x=1;x+3y+4z=k;x+5y+10z=k2 has solution?find the solution in each case. [roorkee 97] SOLVED
2.true/false(plz give reasoning as well):
i.graphite is a better lubricant on moon than on earthans:F SOLVED
ii.CCl4 is inflammable. ans:F SOLVED
3.complete the reaction: SOLVED
Zn+dil HNO3→
Will add more later.
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40 Answers
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39Thermal de broglie wavelength is given by
h, 2pi and k are constants. So,
\frac{\lambda_{1}}{\lambda_{2}} = \frac{\sqrt{m_{2}T_{2}}}{\sqrt{m_{1}T_{1}}}
Mass of a helium atom is four times mass of hydrogen atom. Let hydrogen be 1st atom and helium be 2nd. So we get\frac{\lambda_{1}}{\lambda_{2}} = \frac{\sqrt{4 . 400}}{\sqrt{1 . 300}} = \frac{4}{\sqrt{3}} = 2.30
which is nowhere in the answer :D (temperature in kelvin)
39Since the base is greater than 1, this logarithm is an increasing function.
Firstly, our first restriction is
R1 : sin(x/2) > 0
Or x/2 lies in first or second quadrants.
Or x/2 belongs to [0,pi].
Or x belongs to [0,2pi]
-1 = -log22
So log2(sinx/2) < -log22
Or log2(sinx/2) < log2(1/2)
Since log is increasing,
R2 : sinx/2 < 1/2 (inequality sign will not change)
Or x/2 < pi/6
Or x < pi/3
R1 intersection R2 gives x belongs to [0,pi/3)
Not sure of this..not done domain questions in a long time.
12 sets :
sin(x/2)>0
sin(x/2)<1/2
so soln. set is 0<sin(x/2)<0.5
or 0<x/2<pi/6
so 0 < x < Î /3
1pritish,the ans for 7 is given as:
(4nÏ€,(12n+1)Ï€/3)Ï
((12n+5)π/3,4nπ+2π) [7][11]
18.Fiitjee multi correct:
F2 is a better oxidant than Cl2 in aq solution.this is due to: ans:a,b,d SOLVED
a)heat of dissociation b)electron affinity c)IP d)heat of hydration
fiitjee single correct:
9. 