Chemistry_Today_April_2017_vk_com_stopthepress

(a) The particles will collide the plane with same speed
(b) The time of flight of each particle are same
(c) Both particles strike the plane perpendicularly
(d) The particles will collide in mid air if projected
simultaneously and time of flight of each
particle is less than the time of collision
10. A capacitor is charged to a potential of V 0 . It is
connected with an inductor through a switch S. The
switch is closed at time t = 0. Which of the following
statement(s) is/are correct?
L
S
(a) The maximum current in the circuit is C V
0
L
(b) Potential across capacitor becomes zero for the
first time at t =π LC
(c) Energy stored in the inductor at time t = π LC
2
is 1 2
CV0
4
(d) Maximum energy stored in the inductor is
1 2
CV0
2
11. H + , He + and O + all having the same kinetic
energy pass through a region in which there is
a uniform magnetic field perpendicular to their
velocities. The masses of H + , He + and O + are
1 amu, 4 amu and 16 amu respectively. The
(a) H + will be deflected most
(b) O + will be deflected most
(c) He + and O + will be deflected equally
(d) all will be deflected equally.
12. In the two cases shown, the coefficient of kinetic
friction between the block and the surface is the
same and both the identical blocks are moving with
the same uniform speed. If sinq = mg/4F 2 , then
F F 1 2
(a) F 1 = F 2 (b) F 1 < F 2 (c) F 1 > F 2 (d) F 1 = 2F 2
13. The tension in a stretched y
string fixed at both ends
is changed by 2%, the
fundamental frequency is A B
found to get changed by
15 Hz. Select the correct
statement(s)
C
x
(a) Wavelength of the string of fundamental
frequency does not change.
(b) Velocity of propagation of wave changes by 2%.
(c) Velocity of propagation of wave changes by 1%
(d) Original frequency is 1500 Hz.
14. A charged particle with velocity v= xi
̂
+ yj
̂
moves
in a magnetic field B= yi
̂
+ xj
̂
. The magnitude of
magnetic force acting on the particle is F. Which
one of the following statement(s) is/are correct?
(a) No force will act on particle, if x = y.
(b) F ∝ (x 2 – y 2 ) if x > y.
(c) The force will act along z-axis, if x > y.
(d) The force will act along y-axis, if y > x.
SECTION 3 (Maximum Marks : 12)
• This section contains TO paragraphs.
• ased on each paragraph, there are TO questions.
• Each question has FOUR options (a), (b), (c) and (d). ONLY ONE
of these four options is correct.
• For each question, darken the bubble corresponding to the
correct option in the ORS.
• For each question, marks will be awarded in one of the following
categories :
Full Marks : +3 If only the bubble corresponding to the correct
option is darkened.
Zero Marks : 0 In all other cases.
PARAGRAPH 1
A rod of length 1 m is rigidly clamped at its midpoint.
Longitudinal stationary waves are set up in such a
manner that there are two nodes on either side of the
midpoint. The amplitude of antinode is 2 µm.
15. What is the frequency of the rod if Young’s modulus
of the rod is 2 × 10 11 N m –2 and the density of rod is
8000 kg m –3 ?
(a) 3125 Hz
(b) 6250 Hz
(c) 12500 Hz
(d) 25000 Hz
16. Write the equation of motion at a point 2 cm from
its midpoint.
(a) 2 × 10 –6 cos2.6sin25000t
(b) 10 –6 cos1.3sin25000t
(c) 10 –6 cos1.3sin12500t
(d) 2 × 10 –6 cos1.3sin12500t
PARAGRAPH 2
An object at rest remains at rest and an object in
motion will continue its motion with a constant
velocity unless it experiences a net external force. But
the magnitude of force given by Newton’s 2 nd law and
3 rd law represents or gives the information about the
nature of force. The second law gave a specific way of
determining how the velocity changes under different
influences called forces. There are so many forces
calculated by Newton’s law such as normal force,
CHEMISTRY TODAY | APRIL ‘17 73