Aiits 2016 Hct Vi Jeem Jeea Main Solutions Solutions

February 3, 2018 | Author: arpita | Category: Trigonometric Functions, Ellipse, Space, Physics & Mathematics, Physics
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AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

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1

JEE(Main)-2016 ANSWERS, HINTS & SOLUTIONS HALF COURSE TEST-VI (Main)

Q. No. 1.

PHYSICS A

CHEMISTRY B

MATHEMATICS A

2.

B

A

A

3.

B

D

B

4.

B

D

A

5.

B

B

D

6.

C

B

A

7.

D

B

8.

A D

D

B

9.

C

B

B

10.

B

B

B

11.

D

B

B

12.

B

D

D

13.

B

B

B

14.

B

D

C

15.

A

B

A

16.

C

B

C

17.

C

B

A

18.

D

B

B

19.

D

D

D

20.

B

B

C

21.

D

C

B

22.

C

C

A

23.

C

C

B

24.

C

A

B

25.

A

A

A

26.

C

A

A

27.

C

C

B

28.

C

D

29.

C

A D

30.

B

C

A

B

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AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

Physics

PART – I SECTION – A

1.

Friction force on block A, f K = N = 10 N (opposite to v) 10N 2  acceleration of A =  2.5 m/s (opposite to v) 4kg Time taken by the plank to come at rest, 10 m / s t = 4 sec (using, v = u + at) 2.5 m / s2 2 2 In 4s distance moved by the plank SA = 20 m (using v = u + 2as). To reach the other end block will have to move by 20 m + 40 m = 60 m. As B is moving with constant speed 60 m / s  T  6 sec 10 m / s

2.

Reference frame is at the edge of the plane with the leftward direction as the x-axis. Let x0 be the distance of the cart at t = 0 mg  T = ma T = Ma mg  a= = 2.8 m/s2 Mm Since, M has an initial velocity to the left, a is in fact retardation for M.  V = 7 + (2.8)  5 = 7 m/s i.e. after 5 sec the cart will have the same speed but in opposite direction. 1 x = x0 + 7  5 + (2.8)  5 2 x = x0 + 35  35 = x0 Let the cart go by S to the left from its initial position 02  72 = 2(2.8)  S  S = 8.75 m  Distance covered in up and down journey = 8.75 + 8.75 = 17.5 m

3.

Let the pressures be P1 and P2 of the spheres having initial temperatures 0C and 20C respectively then. n 1 293 Initially P1 = P2   n 2 273 P1 ' 283 293    1  P1 '  P2 ' P2 ' 303 273 thus the mercury pellet will be displaced towards the sphere at higher temp.

If P1 ',P2 ' be the pressures after rasing temperature then

4.

No eddy current form in case (i) & (ii) and hence motion is not opposed.

7.

(1.2  103  10  10  10 2 )  (103  10 4 )  F = Buoyant force – weight  F = 20 N in down ward direction

8.

Kinetic energy is maximum at centre.

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AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

2

10.

1  mgx  1 dU     A.dx 2  LA  y l

U

 U 12.

13.

14.

1 m2 g 2 A 2 x dx 2 L2 A 2Y 0

m2 g 2l . 6 AY

A node is a point where there is no vibration. There is vibration at other points where nodes are not formed.     2Rb  b b dr W   F.dr    .d r   | d r |  = 2  bJ. | dr | R R R

Using A1v 1 = A2v2 and Bernoulli’s principle we get

……(i)

1 1 P1  v12  P2  v 22 2 2

…..(ii)

From (i) and (ii)

v1  A 2

2(P1  P2 ) (A12  A 22 )

Rate of flow = A1v1  A1 A 2

2(P1  P2 ) (A12  A 22 )

But P1 – P2 = P  rate of flow of glycerine  A1 A 2 15.

16.

2P (A12  A 22 )

In adiabatic compression, the temperature always increases and since PV = nRT, the quantity PV also increases. V = 0 + (0.4 × 10) t = 1 m/s. 1 t   .25 second. 4 WfK  WF  K  0

N (u=0) fK

WF   WfK  (fK  S  cos180)  fK  S

10g 10g fK

= (0.4 × 10 × 10) × .25 × 1= 40 × .25 = 10 J. F v=1m/s

17.

At the farthest point X, mv0R = mv x 4R 1 GMm 1 GMm m v2x  = mv 02 2 4R 2 R  v0 = 1.6 gR .

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AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

18.

19.

20.

T = period  2

m 10   2  s. K1  K 2 360 3

The maximum velocity is always at equilibrium position since at any other point there will be a restoring force attempting to slow the mass. impulse 50  Vmax    5ms 1 mass 10 V 5 5 A  amplittude= max   m. (2  )  6   3   3 Their average translational K.E. is kB T, kB  Boltzmann's constant 2 1 1 3 2 2 mH2 CH2  mHe CHe = kBT 2 2 2 CH2 : CHe = mHe : mH2 = 4 : 2 = 2 : 2 7 5 R R 2 2 3 For the mixture,  = (1)  (2) 5 3 2 CV  CV R R 2 2 Applying TV - 1 = constant, the temperature increases by a factor of (2) C(1) P  CP

8.

21.

Impulse = Force  time; net momentum of the system is conserved as the net force on it is zero.

22.

Since velocity of man w.r.t trolley is greater than velocity of trolley w.r.t. earth, after the man turns back displacement of the man will decrease, so maximum displacement will be at the moment when man turns back. L  t 1.5V L 5  Displacement  (v  1.5v)t  2.5v  L 1.5v 3

23.

pV1/4 = constant RT 1/4  v = constant V 3 -3/4 dT V - dV.V 7/4 .T = 0 4 dQ dU dV 4V 5 4 C=  P  Cv  p.  R R  dT dT dT 3T 2 3

24.

or TV-3/4 = constant or

dV 4 V  dt 3T

23 R. 6

 (for first harmonic) 4l1 3 v= (for third harmonic) 2l3 l 1  1 = 6 l3 v=

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5

25.

velocity of upper block when lower block hits a obstacle, F F v  2a.  2.  2M M now after collision retardation of upper block w.r.t. earth, Mg a  g M  v 2  u2  2as  0

26.

AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

F  F  2g.    . M 2 Mg

1 2 I 2 Let x is the distance of CM from A I  M.x2  4M(  x)2 and if I is minimum, W will be minimum w



dI  2Mx  4M  2(   x)  ( 1) = 2 Mx – 8M (  x) dx

dI  10Mx  8M dx  10Mx  8M  0 x

4 . 5

27.

Total internal energy of system will remain conserve nCV1 T1  nCV2 T2  nCV1  nCV2  T 3   5R   3R 5R   2 R  300   2  600   2  2  T       3900  9  30  T  100  8 = 487K (approx) 8   3 3  E   R   487  300  187   R = 280.5 R 2 2 

28.

Let initial velocity of the shot be u and P denote the force of resistance of penetration. In the 1st case plate is fixed 1  0  mu2  PS(COE) …(i) 2 nd In the 2 case plate is free to move. The shot will penetrate up to both acquire a common velocity V (say), there will be no further penetration thus P seases to act 1 1 (M  m)V 2  mu2  PS'(COE) …(ii) 2 2 and (M  m)V  mu(COLM) …(iii) From equation (iii) and (ii) 1 m 2 u2 1  mu2  PS ' 2 (M  m) 2 1 M  mu2   PS' …(iv) 2 (M  m) equation (i) and (ii)

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AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

S' M  S (M  m) SM  S'  . (M  m) (COE = conservation of energy) (COLM = conservation of linear momentum). 29.

Stress =

T 1 E= Stress × Strain × Volume A 2 2

Stress 1  Stress  = Y, E = × Volume Strain 2 Y

T = (L –x) 

30.

F x

2

L

F = ma, E =

dx

1 L–x F 1  2  L A  Y A dx o F F 2L L – x = = F M 6YA L

0  at  0 0  t  0 

v a r   0  2



v 1  0r 2

 

  at 0  t

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7

Chemistry

AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

PART – II SECTION – A

4.

Na  1s2 2s2 2p6 3s1 3s1 orbitals has n = 3,   0 Number of radial nodes = n  – 1 = 3 – 0 – 1 = 2

6.

7.

rO2 rCH4



PO2

MCH4

PCH4

MO2



nO2 nCH4

16 3 16 16 3 =   32 32 2 32 4 2

Half life t1/2 = 140 days 280  140 3 140

Number of half lives in total time = R = R0(1/2)n  3000 = R0(1/2)3, R0 = 24000 dps 9.

11.

58  1.63 0.082  300 Mass of Al(s)  0.05 101 20  20  61.13  13.56 gm nCl2 

So mass of Al(s) dissociated = 0.5 moles So eq is established 3   Al(s)  Cl2(g)   AlCl3(s) 2 3 1.63   0.5 0.5 2 3

3  0.88  0.082  300  2  K p  PCl2     2.7 2     8 (Volume of the vessel is taken 8 lit approx even after eq is established). 

13.

HO

3 2

OH 2

B HO 14.

OH

HO

CH2

HO

CH2

H2C

O

O

 

CH2  4H2 O

B H2C

O

(i)

Na2 S2 O3  2HCl   2NaH  SO2  H2 O  S

(ii)

KI3  2Na2S2 O3   KI  2NaI  Na 2S4 O6

(iii)

2AgNO3  Na2 S 2O3   Ag2 S2 O3  2NaNO3

O

CH2

white

H2O   Ag2 S  H2 SO4

Black

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AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

15. 16.

Stability of intermediate carbocation increases rate of reaction. CH3

CH3

CH3

CH3

NH2  

NH2   NH3



H 

Cl

NH2

NH2

18. O

O

(Aromatic)

O

19. O

C OH

KMnO4    H

O

O OH

21.

Mg2 C3  2H2 O   MgOH2  CH3  C  CH

24.

pOH  pKb  log10

NH4 Cl 0.1  4.7  log  5.7 NH OH 0.01  4 

pH = 14 – 5.7 = 8.3

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9

Mathematics

AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

PART – III SECTION – A

1.

The equation of the line joining A(1, 0) and B(3, 4) is y  2x  2 . This

8 6 cuts the circle x 2  y 2  4 at Q(0,  2) and P  ,  . 5 5 7 3 We have BQ  3 5, QA  5, BP  and PA  5 5



BP 7 / 5 7 BQ 3 5   and     3 PA 3 / 5 3 QA  5

Y

B(3,4) P(8/5,6/5)

X

O

A(1,0)

X

Q(0,–2) Y

 ,  are roots of the equation x 2  x(  )    0 7  7 i.e., x 2  x   3   (3)  0 or 3x 2  2x  21  0 . 3  3 2.

ax2 + by2 + 2fx + 2gy + c = 0 2fx    2 2gy  a  x2    b y  c 0 a b     2 2  f 2 g2  f g    a x    b y      c a b b   a  2 2 (x  f / a) (y  g / b)  2  2 1 f  f  g2 g2 c / a    c / b   b b a  a 

 f 2 g2   f 2 g2   c   c   a b a b   (1  e2 ) i.e. e is eccentricity, then  b a

 1  e2 

3.

a ba ba  e2  e    b b  b 

(1  3x)1/2  (1  x)5/3  x 2 1    4

1/2

 1 1 1 1   5 521  2 2 1  2 (3x)  2   2  2 ( 3x)  ....  1  3 (  x)  3 3 2 ( x)  ....       2  1 x  1 1 1 x   2 1             ....  2  4  2  2  2  4   53 2  19  1  12 x  144 x  ....    1  35 x  ....  x 1 24   2 1  2  8 x  ....   Neglecting higher powers of x , then 35 35 a  bx  1  x  a  1,b   . 24 24

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AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

4.

A(0,0)

y  mx . It makes an angle of 45o with 2x  3y  6 .

m  ( 2 / 3)  1 1  m( 2 / 3) 1 or 3m  2  (3  2m)  m  , 5 5 Hence sides are x  5y  0, 5x  y  0 and 2x  3y  6 . Solving in pairs, vertices are (0,0) , 

90°

tan( 45o ) 

B

45°

45° (2x+3y=6)

C

 6 30   30 6   13 , 13  ,  13 ,  13  .    5.

L12  x  3y  1  0 L 23  2x  y  12  0 L13  3x  2y  4  0 Therefore, the required distances are 4  3 4 1 7 D3   10 10 D1  D2 

6.

4  1  12 5



7 5

3 5  2 2  4 94



7 13

.

The equation of any line passing through the given point P(3, 4) and making an angle

 with 6

x3 y4   r (say) ......(i) cos 30o sin30o Where ‘r’ represents the distance of any point Q on this line from the given point P (3, 4). The coordinates (x, y) of any point Q on line (i) are  r 3 r (3  r cos30o ,4  r sin30o ) i.e.,  3  ,4   2 2  If the point lies on the line 12x  5y  10  0 , then

x-axis is

 r 3 r 132  12  3  .   5  4    10  0  r  2 2 12 3  5     7.

Suppose a point on circle is B(x1, y1 ) and that which divides A and B in 3 : 2 is P given by h

2  3x1 2  3y1 5h  2 5k  2 ,k  or  x1 ,  y1 5 5 3 3

As (x1, y1 ) lies on circle x 2  y 2  4 , we get on substituting, 25(x 2  y 2 )  20(x  y)  28  0 .

8.

(y - 3)2 = -4 (x - 3) (given equation of parabola)  equation of latus rectum is x = 2.

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9.

AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

x  t 2  t  1and y  t 2  t  1  x  y  2  2t 2 and x  y  2t  2(x  y  2)  (x  y)2  x 2  y 2  2xy  2x  2y  4  0 Comparing with the equation ax 2  2hxy  by2  2gx  2fy  c  0, abc  2fgh  af 2  bg2  ch2  0 and h2  ab

10.

Since the number of students giving wrong answers to at least i question (i  1, 2,........,n)  2ni . The number of students answering exactly i (1  i  1) questions wrongly = {the number of students answering at least i questions wrongly, i  1, 2, .........,n)} – {the number of students answering at least (i  1) questions wrongly (2  i  1  n)}  2ni  2n(i1) (1  i  n  1) . Now, the number of students answering all the n questions wrongly  2nn  20 . Thus the total number of wrong answers  1(2n 1  2n 2  2(2n 2  2n3 )  3(2n3  2n 4 )

11.

We have, y  z  a(cos2 x  sin2 x)  c(sin2 x  cos2 x)  a  c ( solution is (b)}

y  z  a(cos2 x  sin2 x)  4b sin x cos x c(cos2 x  sin2 x)  (a  c)cos2x  2b sin2x  1  tan2 x   2 tan x   (a  c).    2b.   2 2 1  tan x  1  tan x    2 2  2.2b / (a  c)   1  4b / (a  c)   (a  c).   2b.  2 2 2 2 1  4b / (a  c)  1  4b / (a  c) 

Since tan x  yz  

2b , (a  c)

(a  c).{(a  c)2  4b 2 }  8b 2 (a  c) (a  c)2  4b2

(a  c)(a  c)2  4b2

{(a  c)2  4b2 }  y  z,( a  c) .

12.

 (a  c)

Given that z2  (p  iq)z  r  is  0 ......(i) Let z   (where  is real) be a root of (i), then

 2  (p  iq)  r  is =0 or  2  p  r  i(q  s) =0 Equating real and imaginary parts, we have  2  p  r  0 and q  s  0 2

 s   s  Eliminating , we get    p    r  0  q   q 

or s2  pqs  q2r  0 or pqs  s2  q2r

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12

AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

13.

 1 t2 x  3 2  1 t

 2t , y  1  t2 





2

1  t 2  4t 2 x2 2 y   1 Which is an ellipse 2 9 1 t2

  1 8  1  9 1  e   e  1   9 9 2

2

3 5 Hence foci of the ellipse are ( 3, 0) Hence PF1 + PF2 = 10.

14.

Here a = 5, b = 4 and e =

15.

The given ellipse is



 3  4 1  e2



x2 y 2   1  a  2,b  3 4 3 1 e 2

1 1 2 Hence, the eccentricity e1, of the hyperbola is given by

 ae  2 





1  e1 sin   e1  cosec  b2  sin2  cosec 2   1  cos2  2

Hence, equation of hyperbola is

2

x y   1 or x 2 cosec 2   y 2 sec 2   1 2 sin  cos2 

16.

Since (n+2)th term is the middle term in the expansion of (1  x)2n 2 , therefore p  2n 2Cn1 . Since (n+1)th and (n+2)th terms are middle terms in the expansion of (1+x)2n+1, therefore q  2n1Cn and r  n1Cn1 But n1Cn  2n1Cn1  2n 2Cn1  qr  p

17.

For the first set number of ways

52

C17 . Now out of 35 cards left 17 cards can be put for second in

C17 ways similarly for 3 in 18 C17 . One card for the last set can be put in only one way. Therefore the required number of ways for the proper distribution 52! 35! 18! 52!     1!  . 35!17! 18!17! 17!1! (17!)3 35

18.

19.

rd

  tan(cot x)  cot(tan x)  tan(cot x)  tan   tan x  2     (70)2  20h  h2  (6)(70)(20) cot x  n   tan x  cot x  tan x  n  2 2 2  2 4 2 2 (70)  20h  h  (6)(70)(20) .  n   sin2x    (2n  1) sin 2x 2 n  2

1  sin x  sin2 x  ....  4  2 3

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13



AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

1 1  4  2 3  sin x  1  1  sin x 42 3

(4  2 3) 2 3 3   4 4 2  2  x  or . 3 3

 sin x  1 

20.

Adding and subtracting the given relation, we get (m  n)  a cos3   3acos  sin2   3a cos 2  . sin   a sin 3 

 a(cos   sin  )3 and similarly (m  n)  a (cos   sin  )3 Thus, (m  n)2/3  (m  n)2/3

 a2/3 {cos   sin  )2  (cos   sin  )2 }  a2/3 {2(cos2   sin2  )}  2a2/3 . n sin A  1 sinB A B A B 2cos sin n  1 sin A  sinB 2 2    A B A B n  1 sin A  sinB 2sin cos 2 2 A B A B  tan cot 2 2 n 1 A B  A B   tan    tan 2 . n1 2  

21.

We have sin A  nsinB 

22.

We have equal roots, therefore 2  4 . Now second equation x 2  x  12  0 has a root 2, so put x  2  4  2  12  0    4 16 Hence from 2  4 , we have   4 4  (, )  (4,4) .

23.

Let the roots are  and n b b Sum of roots,   n       a a(n  1) c c and product, .n    2  a na From (i) and (ii), we get

.....(i) ....(ii)

2

 b  c b2 c       2 2 a(n  1) na na a (n  1)  

 nb2  ac(n  1)2 . Note: Students should remember this question as a fact.

24.

We have

3  i  (a  ib)(c  id)

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AIITS-HCT-VI-PCM(Sol)-JEE(Main)/16

 ac  bd  3 and ad  bc  1 b d -1  tan1   Now tan  a  c   b d       bc  ad  1  1   tan1  a c   tan1    n  ,n  I   tan  b d 6  ac  bd   3  1  .  a c 

25.

We know that loga m  loga n  m  n or m  n , according as z  x  iy log(1/3) | z  1|  log(1/3) | z  1|| z  1|  | z  1|

a  1 or 0  a  1 . Hence for

1    0   1 3  

| x  iy  1|| x  iy  1|  (x  1)2  y 2  (x  1)2  y 2  4x  0  x  0  Re(z)  0 26.

x 2n1  y2n1 is always contain equal odd power. So it is always divisible by x  y .

27.

 n  1 Check through option, the condition    n! is true for n  1 .  2 

28.

H  d tan  and H  h  d tan 

n

60 tan   60 tan  60 tan    h  60  h tan  tan  60 sin(   )  h  x  cos  sin  . sin  cos  cos  cos 



29.

h  T2 A  h T2 A Hence 120  h  30  h  h  45 m.



H=60m

h

 d

T2

tan 45o  1 

T1

h

h 45° T2

30.

45° A 30 B 120 m

T1

x  1  1  1  ..... to  

We have x  1  x  x2  1  x  x2  x  1  0

1 1 4 1 5  2 2 1 5 As x  0 , we get x  2  x

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