RBT 5 - Paper 1
RBT 5 - Paper 1
QP CODE: PAPER - 1
Time Allotted: 3 Hours Maximum Marks: 204
▪ Please read the instructions carefully. You are allotted 5 minutes specifically for
this purpose.
▪ You are not allowed to leave the Examination Hall before the end of the test.
BATCHES – Two Yr CRP224(All)
INSTRUCTIONS
Caution: Question Paper CODE as given above MUST be correctly marked in the answer
OMR sheet before attempting the paper. Wrong CODE or no CODE will give wrong results.
A. General Instructions
1. Attempt ALL the questions. Answers have to be marked on the OMR sheets.
2. This question paper contains Three Sections.
3. Section-I is Physics, Section-II is Chemistry and Section-III is Mathematics.
4. All the section can be filled in PART-A & B of OMR.
5. Rough spaces are provided for rough work inside the question paper. No additional sheets will be
provided for rough work.
6. Blank Papers, clip boards, log tables, slide rule, calculator, cellular phones, pagers and electronic
devices, in any form, are not allowed.
(ii) PART–A (05–12) contains Eight (8) Multiple Choice Questions which have One or More Than One
Correct answer.
Full Marks: +4 If only the bubble(s) corresponding to all the correct options(s) is (are) darkened.
Partial Marks: +1 For darkening a bubble corresponding to each correct option, provided NO incorrect
option is darkened.
Zero Marks: 0 If none of the bubbles is darkened.
Negative Marks: −2 In all other cases.
For example, if (A), (C) and (D) are all the correct options for a question, darkening all these three will result
in +4 marks; darkening only (A) and (D) will result in +2 marks; and darkening (A) and (B) will result in −2
marks, as a wrong option is also darkened.
(iii) PART – B (1 – 3): This section contains Three (03) questions. The answer to each question is a NON-NEGATIVE
INTEGER. Each question carries +3 marks for correct answer and -1 marks for wrong answer.
(iv) Part-B (4 – 8) contains Five (05) Numerical based questions, the answer of which maybe positive or
negative numbers or decimals TWO decimal places (e.g. 6.25, 7.00, -0.33, -.30, 30.27, -127.30) and each
question carries +3 marks for correct answer. There is no negative marking.
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PART – A (Maximum Marks: 12)
This section contains FOUR (04) questions. Each question has FOUR options. ONLY ONE of these four
options is the correct answer.
1. A paper ball (assumed to be carried easily by wind) is to be thrown in a trash can located
6 3
m north of the point of projection. Wind is blowing towards east with speed 2 m/s. The
5
paper ball is thrown at an angle 37 with the horizontal and it falls on the trash can. What is
the speed with which it was thrown?
(A) 4 m/s (B) 5 m/s (C) 6 m/s (D) 7 m/s
0 0 0
(A) V 2 (B) V 2 (C) V (D) zero
2 2 2
(C) l0 / 3 (D) I0 / 2
-I0
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9. Two projectile are thrown at the same time from two different points. The projectile thrown
from the origin has initial velocity 3iˆ + 3jˆ with respect to earth. The projectile has initial
velocity aiˆ + bjˆ with respect to earth thrown from the point (10, 5). ( î is a unit vector along
horizontal, ĵ along vertical). If the projectile collides after two second, then the
1
(A) value of a is -2 (B) value of a is
2
1
(C) value of b is (D) value of b is –2
2
11. In the given figure, the block is attached with a system of three
A
ideal springs A, B, C. The block is displaced by a small
distance x from its equilibrium position vertically downwards k
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12. The distance between a screen and an object is 120 cm. A convex lens is placed closed to
the object and is moved along the line joining object and screen, towards the screen. Two
sharp images of the object are found on the screen. The ratio of magnification of two real
images is 1 : 9. Then,
(A) focal length of the lens is 22.5 cm.
(B) smaller image is brighter than the larger one.
(C) larger image is brighter than the smaller one.
(D) brightness of both the images is same.
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4. A ring of mass 3.15 kg is rolling without slipping with linear velocity 1 m/sec on a smooth
horizontal surface. A rod of same mass is fitted along its one diameter. Find total kinetic
energy of the system (in J).
x3 9x2
5. Potential energy of a particle moving along x-axis is given by U = − + 20x . Find out
3 2
position of stable equilibrium state.
8. 2 kg of ice at –22.50C is mixed with 2.5 kg of water at 250C in an insulating container. If the
specific heat of ice and water are 0.5 cal/gm°C and 1 cal/gm°C respectively. Latent heat of
fusion of ice = 80 cal/gm. Find the amount of water present in the container (In kg).
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PART – A (Maximum Marks: 12)
This section contains FOUR (04) questions. Each question has FOUR options. ONLY ONE of these four
options is the correct answer.
2. R − C C − R ⎯⎯⎯→
LiAlH4
RCH = CHR
In the above reaction, R and R should be
(A) R = CHO and R = CH3 (B) R = CH3 and R = CH2OH
(C) R = C2H5 and R = CO (D) R = CH3 and R = COOH
3. The S – O bond order of SOF2 is greater than that of SOCl2. This is due to
(A) polarity of O – F bond is greater than that of O – Cl bond
(B) the O → S back bond in SOF2 is stronger than that in SOCl2
(C) the S → O back bond in SOF2 is stronger than that in SOCl2
(D) the FSF is greater than ClSCl
OH
(C) (D) OH
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6. Compound A(C5H7OCl) reacts rapidly with ethanol and catalytic amount of acid to form a
pleasant smelling substance B(C7H12O2). A also reacts with H2O to form C with neutralization
equivalent of 100. A, B and C all react with Br2 water. Acid C, which can also be obtained by
acidic hydrolysis of B is oxidized to new acid D(C4H6O3) and CO2. D on heating with soda
lime gives acetone. Identify A to D.
(A) A = CH3 - C - CH 2 - C- Cl (B) B = CH3 - C - CH 2 - C - OEt
CH2 O CH2 O
(C) C = CH 3 - C - CH 2 - C - COOH (D) D = CH 3 - C - CH 2 - COOH
CH2 O O
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8. The spectra of which complex(s) is/are spin forbidden as well as Laporte forbidden?
(A) [Mn(H2O)6]2+ (B) [Fe(H2O)6]3+
3-
(C) [Co(CN)6] (D) [Cr(NH3)6]3+
O O
H3C CH3
CHO
10. Which of the following reactant(s) produce(s) racemic mixtures when treated with HBr?
(A) Cis-2-butene (B) Trans-2-butene
(C) 1-butene (D) Isobutene
11. Which of the following increases by increasing the temperature of a chemical reaction?
(A) Rate constant (B) Half-time
(C) Rate of reaction (D) Temperature coefficient
CH3
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1. OCH 3
OCH 3
HI
⎯⎯⎯ → Products
OCH 3
OCH 3
If x moles of HI can be completely consumed by one mole of the above compound, what is
the value of x?
3. If the pH of 0.1 M aqueous solution of NH4NO3 is x, what is the value of x? [Kb of NH4OH =
10–5]
4. 2.5 mole of KCl is added to one Kg of water at 1 atm. At what temperature in kelvin unit will
the water boil if the degree of dissociation of KCl is 0.8? [Kb of H2O = 0.52 K kg mol–1]
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7. The molecular mass of a polyhydric aliphatic alcohol, increases by 252 unit if it reacts with
CH3COCl/(CH3CO)2O. if the number of OH groups present in the alcohol is x, what is the
x
value of ?
4
8. A 2 ( g) ⎯⎯→ A ( g) + A ( g )
The heat of reaction of above decomposition of a diatomic molecule A2(g), into monoatomic
gases A(g) is 40.5 kJ mol-1 at 320 K. What will be the enthalpy change of the reaction at 330
K in kJ mol–1 unit?
5R
[CP of monoatomic gases = ]
2
7R
[CP of diatomic gases = ]
2
[R = 8.3 J K-1 mol-1]
Space For Rough Work
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MAAT
THHE
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ATTIIC
CSS
PART – A (Maximum Marks: 12)
This section contains FOUR (04) questions. Each question has FOUR options. ONLY ONE of these four
options is the correct answer.
( ) = x + f, then x (1 − f ) is equal to
2n
2. If x = 7 + 4 3
(A) 1 (B) 2
(C) 3 (D) 4
4. For a b c 0, the distance between (1, 1) and the point of intersection of the lines
ax + by + c = 0 and bx + ay + c = 0 is less than 2 2 . Then
(A) a + b − c 0 (B) a − b + c 0
(C) a − b + c 0 (D) a + b − c 0
5. The number of triangles that can be formed with the sides of lengths a, b and c where a, b, c
are integers such that a b c is
1 1
(A) ( c + 1) when c is odd (B) c ( c + 1) when c is odd
2
4 2
1 1
(C) c ( c + 2 ) when c is even (D) c 2 when c is even
4 4
Space For Rough Work
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1+ x 1 + 2x 1 + 3x
6. If x R, and S = 1 − C1 + C2 − C3 + ... + .. upto (n + 1) terms then S
1 + nx (1 + nx ) (1 + nx )
2 3
7. A and B are two points on the x – axis and y – axis respectively. Two circles are drawn
passing through the origin and having centre at A and B.
(A) Equation of the common chord is ax − by = 0
ab2 a 2b
(B) mid – point of the common chord is 2 . 2
a +b a +b
2 2
b cos x b + sin x
8. The equation = posses a solution if
(
2 cos 2x − 1 cos x − 3 sin2 x tan x
2
)
1 1 1
(A) b (B) 0 b (C) b 0 (D) b =
2 2 2
9. Normals are drawn from the point P (15, 12) to the parabola y2 = 4x . If the feet of the
normal form a ABC, then which of the following is/are true.
26
(A) Centroid of ABC is , 0
3
22
(B) Centroid of ABC is , 0
3
(C) Area of triangle formed by tangents to the parabola at A, B and C is 35 sq. units
(D) Area of triangle formed by tangents to the parabola at A, B and C is 140 sq. units
10. Let z 1 lies on z = 1 and z 2 lies on z = 2 , then which of the following is/are true?
(A) maximum value of z1 + z2 is 3 (B) minimum value of 2z1 − z2 is 0
(C) maximum value of 2z1 + z2 is 4 (D) minimum value of 2z1 − 3z2 is 5
11. If pair of tangents are drawn from centre C of the circle x2 + y2 − 5x = 0 to the nearer branch
x2 y2
of the hyperbola − = 1 to touch it at point A and B, then
25 16
−64
(A) product of the slopes of lines CA and CB is
75
−32
(B) product of the slopes of lines CA and CB is
25
(C) circumcentre of ABC lies inside the ABC .
(D) circumcentre of ABC lies outside the ABC .
Space For Rough Work
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1. Consider the number N = 10! . If the number of positive divisors of N is , then equals
30
2. Let L1,L 2 and L 3 be the length of tangents drawn from a point P to the circles x2 + y2 = 4 ,
x2 + y2 − 4x = 0 and x2 + y2 − 4y = 0 respectively. If L14 = L22L32 + 16, then locus of P are the
curves C1 (a straight line) and C2 (a circle). Let the circumcentre of the triangle formed by C1
and other two lines which are inclined at an angle of 45o with C1 and is tangent to C2 is
( , ) , then ( + 2) equals
3.
n
Let Sn = r .2 2
r
(1+( −1) ).3 2r (1−( −1)r ) . If
r
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1
5. The length of the semi – major axis of an ellipse is 8 and the eccentricity is . If denotes
2
the area of the rectangle formed by joining the vertices of the latera recta of the ellipse then
the value of is equal to
120
6. The centres of two circles C1 and C2 each of unit radius are at a distance of 6 units from
each other. Let P be the mid point of the line segment joining the centres of C1 and C2 and
C be a circle touching C1 and C2 externally. If a common tangent to C1 and C passing
through P is also a common tangents to C2 and C1 , then the one fifth of the radius of the
circle C is
1
7. Value of x if x satisfies the equation log1− x ( 3 ) − log1− x ( 2 ) = is
2
5
The sum of all the integral roots of (log5 x ) + log5x = 1 is ______________
2
8.
x
Space For Rough Work
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QP Code:
Answers
S
SEEC
CTTIIO
ONN –– II :: P
PHHY
YSSIIC
CSS
PART – A
1. B 2. D 3. A 4. C
5. ABD 6. AD 7. AC 8. ACD
9. AC 10. ABC 11. ABCD 12. AB
PART – B
1. 2 2. 5 3. 6 4. 5.25
5. 5 6. 1.25 7. 1.73 8. 3
S
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ONN –– IIII :: C
CHHE
EMMIIS
STTR
RYY
PART – A
1. B 2. B 3. B 4. C
5. ACD 6. ABD 7. CD 8. AB
9. AC 10. ABC 11. ACD 12. ABC
PART – B
1. 7 2. 4 3. 5
4. 375.34 (Range 375.2 to 375.4) 5. 12.5 (Range12.4 to 12.6)
6. 55.8(Range 55.7 to 55.9) 7. 1.5
8. 40.62(Range 40.6 – 40.7)
S
SEEC
CTTIIO
ONN –– IIIIII :: M
MAATTH
HEEM
MAATTIIC
CSS
PART – A
1. A 2. A 3. D 4. A
5. AC 6. CD 7. ABCD 8. ABC
9. AC 10. ABC 11. AC 12. AC
PART – B
1. 9 2. 0 3. 4 4. 2.50
5. 0.8 6. 1.6 7. –1.25 8. 6
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2. D
Sol. B = 0
dB
B⊥S ; =0
dt
3. A
Sol. vy = 2gH V0
vy 2gH H
= = tan 60o = 3
90°
vx vo Vo
60°
Vy V
2gH
v0 = 30°
3
4. C
2Io
Sol. i= t [0 < t < t/2]
T
T/2
2Io
t dt
2
T 0 Io
irms = = .
T/2 3
5. ABD
Sol. Results can be obtained by looking at shape of string
after a short time (shown dotted). Also, each particle
of string executes SHM about mean position which is
on x-axis.
6. AD
Sol. Use ampere`s law to find magnetic field due to solid cylinder current = µ0Jd/2
Due to cylinder on its own axis is 0
Applying superposition principle we can get the required answers.
7. AC
Sol. Force on branch BC is coming out of the plane of paper and force on AD is going into the
plane of paper and net force on the loop is zero.
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8. ACD
Sol. ( )
Fm = q v B and apply Newton’s second law of motion.
9. AC
Sol. b 3-a
w.r.t. A
B
a 3-b
3 5
3 5
A
(0, 0) 10
(0, 0) 10
d
In vertical direction s =
t
5 1
3−b = → b =
2 2
In horizontal direction
10
3−a = → a = −2.
2
10. ABC
Sol. So, its radius is also R.
mv mv
So, R = → B=
qB qR
2M m
T= =
4qB 2qB
So, A, B & C are correct.
11. ABCD
Sol. Let elongation in spring A, B and C be x1, x2 and x3 respectively.
Considering spring forces and constraint relations
x2 = 4x3 …(i)
x2 = 2x1 …(ii)
and x1 + 2x2 + x3 = x …(iii)
2 4 1
x1 = x ; x 2 = x ; x 3 = x
11
11 11
x
Also, F = 2K
11
11m
T = 2
2k
12. AB
Sol. For two different positions of lens
u 120 − u
u 120 – 4 1= ; 9=
120 − u u
2
1 u 1 u
= → =
9 (120 − u) 2
3 120 − u
u = 30 ; v = 90
120
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1 1 1 1 1
= − = +
f v u 90 30
P = 22.5
PART – B
1. 2
Sol. Let elongation of spring be x0 in equilibrium. Then,
2T + mgsin = 2kx0 …(i)
and T = mg …(ii)
2k(x0 + 2x)
Let Block B is displaced by x down the inclination
F.B.D. of B aB
−maB = 2k(x0 + 2x) − 2T − mgsin …(iii)
2T
F.B.D. of A mg sin
mg – T = maA T
Also, a A = 2aB
T = mg − 2maB aA
−maB = 2kx0 + 4kx − 2mg + 4maB − mgsin
−maB = 4kx + 4maB m
g
4k
aB = − x
5m
5m
T = 2
4k
T = 6.28 s.
2. 5
Sol. Conservation of mechanical energy
1
mgH = mgh + mv 2
2 V
R 1
0.45 mg = 3mg + mv 2
B
2 2 R/2
60°
A
9 – 30R = v2 …(i) C
60°
R 3
AC =
2
. For reaching at B let particle takes t sec.
v R 3
t = …(ii)
2 2
v 3 1 R
t − g t2 = …(iii)
2 2 2
On solving, v2 = 15R by eq. (i)
9
9 – 30R = 15R R= 100 = 20 cm
45
= 1/5 meter.
3. 6
r
Sol. dF = ( 2rdr ) 2
h
dP = dF. V
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4
( r ) r dr
2
=
h
P 42 R 3 2R 4
o dP =
h o
r dr =
h
x+y=6
4. 5.25
1 1 1 m(2r)2 2 1 2 2
Sol. K.E. = mv 2 + mv 2 + w + mr w = 5.25.
2 2 2 12 2
5. 5
Sol. At stable equilibrium, U is minimum.
dU d2U
= 0 and >0
dx dx 2
1 x3 ax 2
= − + 20x = 0.
dx 3 2
x – 9x + 20 = 0. (x – 5) (x – 4) = 0.
2
dx = dt
o o
And 3 – 10 k to = 0
7. 1.73
Sol. = NIAB = C
NABQ
=
C
So, K = 3
K = 1.73
8. 3
Sol. 2000 × 15 × 0.5 + m × 80 = 2500 × 25 × 1
m = 500 gm
Water = 2.5 kg + 0.5 kg = 3 kg.
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CTTIIO
ONN –– IIII :: C
CHHE
EMMIIS
STTR
RYY
PART – A
1. B
Sol. Back bonding in BCl3 is easier as it is electron deficient compound. Between OCl2 and NCl3
the electronegative difference between atoms in OCl2 is greater than between atoms in NCl3.
OCl2 forms stronger back bond than NCl3.
2. B
Sol. R or R can’t be CHO, CO, COOH as they are reduced by LiAlH4.
3. B
Sol. The O → S back bond in SOF2 is stronger than O → S in SOCl2. Since F is more
electronegative than Cl, the S atom in SOF2 strongly attract the lone pair of oxygen to form
p - d back bond.
4. C
Sol. No alkene can produce the alcohol in (C) because loss of H2O can’t form any alkene.
5. ACD
Sol. This is Hoffmann’s bromamide reaction.
6. ABD
Sol. The alkene part of the carboxylic acid derivatives reacts with Br2/H2O.
7. CD
Sol. dx 2 − y 2 lie along X- and Y- axis, which are perpendicular to Z-axis.
8. AB
Sol. Due to t 32geg2 crystal field electronic configuration of Mn2+ and Fe3+ ions
9. AC
Sol. Cleavage of C = C bond takes place during ozonolysis.
10. ABC
Sol. Racemic mixture is formed from compounds containing chiral carbon atom.
11. ACD
Sol. t½ only decreases by increasing temperature.
12. ABC
Sol. In A, B and C the products are mesitylene, cyclohexane and benzene respectively.
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PART – B
1. 7
Sol. OCH 3 OH
OCH 3 OH
4 HI
⎯⎯⎯⎯ → + 2 CH3I
OCH 3 OH
OCH 3 OH 2 HI
OH OH OH
I I
⎯⎯ HI
−I2
⎯⎯ ⎯ +2H2O
I
OH OH OH
2. 4
Sol. 4Fe3+ + 12SCN− ⎯⎯
→ 4[Fe(SCN)3 ]
One mole Fe3+ consumes three moles of SCN– ion. Four moles of Fe3+ will consume 4 3 =
12 moles Fe(SCN)3.
x=4
3. 5
1 kw 1 1
Sol. pH = p − pkb − logC = 14 − 5 − log10 −1 = 10 = 5
2 2 2
7. 1.5
O
Sol. ( CH CO) O
ROH + CH3COCl ⎯⎯⎯⎯⎯
3 2
→ R − O − C − CH3 + HCl
For one OH group (OH → OCOCH3), loss of one H and gain of COCH3 takes place.
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S
SEEC
CTTIIO
ONN –– IIIIII :: M
MAATTH
HEEM
MAATTIIC
CSS
PART – A
1. A
Sol. Let − be a common root of f ( x ) = 0 and g ( x ) = 0 . Then 2 = −a − b . Substituting
this in 3 + p + q = 0, we get ( a2 − b + p ) + ab + q = 0
As is irrational and a,b,p,q , p = b − a2, q = −ab . This gives, g ( x ) = ( x − a) f ( x ) .
2. A
1
Sol. We have 7 − 4 3 =
7+4 3
( )
2m
0 7 − 4 3 1 0 7 − 4 3 1
( )
2n
Let F = 7 − 4 3 .
( ) + (7 − 4 3 )
2n 2n
Then x + F = 7 + 4 3
= ( 49 − 48 )
2n
= 12n = 1.
3. D
− sin − cos 1
Sol. Put − − and consider the determinant = cos sin 1
cos ( + ) sin ( − ) 1
Using R3→ R3 − cos R2 − sin R1
− sin − cos 1
= cos sin 1
0 0 1 − cos − sin
= (1 − cos − sin ) cos ( + )
= (1 − cos − sin ) cos ( 2 − )
= 1 − 2 sin + cos ( 2 − )
4
As 0 +
4 4 4 2
1 −
sin + 1 and 0 , 2 −
2 4 4 4 2
cos ( 2 − ) 0
Thus 0 and the points P, Q, R are non – collinear.
4. A
−c −c
Sol. The lines ax + by + c = 0 and bx + ay + c = 0 intersect in , .
a+b a+b
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−c −c
Distance between (1, 1) and ,
a+b a+b
c a+b+c
= 2 1+ = 2 .
a+b a+b
a+b+c
As 2 2 2, we get a + b + c 2 ( a + b )
a+b
a+b−c 0.
5. AC
Sol. Let c = 2m + 1 where m is a positive integer. Since c a + b and a b, we get
1 1
c 2b b c = m + . Thus, b can take values from m + 1 to 2m + 1.
2 2
If b = 2m + 1, a can be 1,2,...... ( 2m + 1) . Thus, there are ( 2m + 1) values.
If b = 2m, a can be 2, 3,….2m. In this case a can take ( 2m − 1) values. And so on. When
b = m + 1, a can take just one value viz. (m + 1) . Thus, there are
( 2m + 1) + ( 2m − 1) + .... + 1 = (m + 1)
2
.
6. CD
1
= y, we can write S = C0 − C1 y + C2 y 2 − ... + ( −1) Cn y n
n
Sol. Putting
1 + nx
− xy C1 − 2C2 y + 3C2 y 2 − ... + ( −1) nCn y n−1
n −1
= (1 − y ) + xy
n d
dt
(1 − t ) t = y
n
= (1 − y ) − nxy (1 − y )
n n −1
= (1 − y ) 1 − y − nxy
n −1
= (1 − y ) 1 − (1 + nx ) y = 0 .
n −1
7. ABCD
x y
Sol. + = 1. Equations of
Let OA = a and OB = b (figure), so that the equation of the line AB is
a b
the circles passing through the origin and having centres at A (a, 0) and B (0, b) are,
respectively.
x2 − 2ax + y2 = 0 (1)
and x2 − 2by + y2 = 0 (2)
so that the equation of the common chord OP is
ax − by = 0 (3)
which is perpendicular to AB
This has one end at the origin O and the other end P is given by solving (2) and (3).
2
b
a y − 2by + y = 0
2
2a2b 2ab2
y= 2 x= 2
a +b 2
a + b2
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P
(0, b)
B
O (0, 0) A (a, 0)
ab2 a 2b
Therefore, the mid – point of the common chord OP is 2 , 2
which lies on AB
a +b a +b
2 2
8. ABC
Sol. The conditions for the existence of a solution are
1
1. 2cos 2x − 1 0 cos 2x 2x
2 6
2. tan x 0 x
2
1
3. cos2 x − 3 sin2 x 0 tan2 x x
3 6
As 2 cos 2x − 1 = 2 ( cos x − sin x ) − 1
2 2
( ) (
= 2 cos2 x − sin2 x − cos2 x + sin2 x )
= cos2 x − 3 sin2 x
So the given equation can be written as b sin x = b + sin x
b
sin x =
b −1
b
Which is possible if −1 1
b −1
2b − 1 1
0 and 0
b −1 b −1
1
2b − 1 0 b
2
1 −
But for b = ,sin x = −1 which is not possible as x .
2 2
1
Hence equation has a solution if b .
2
9. AC
Sol. tx + y = 2t + t3 passes through (13, 12) t3 − 13t − 12 = 0
t 2 ( t + 1) − t ( t + 1) − 12 ( t + 1) = 0
( t + 1)( t − 4)( t + 3) = 0
A, B, C = ( t 2 ,2t )
A (1, − 2) ; B (16,8) ;C (9, − 6 )
1 −2 1
26 1
Centroid = , 0 , Area = 16 8 1
3 2
9 −6 1
A = 70
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70
Area of triangle formed by tangents = = 35 .
2
10. ABC
Sol. z1 = 1 and z2 = 2
(A) z1 + z2 z1 + z2 3
(B) 2z1 − z2 2 z1 − z2 0
(C) 2z1 + z2 2 z1 + z2 4
(D) 2z1 − 3z2 2 z1 −3 z2 4
11. AC
5
Sol. centre: , 0 ; y = mx 25m2 − 16
2
5 25m2
m = 25m2 − 16 = 25m2 − 16
2 4
75m2 64 64
= 16 m2 − = 0, product of slopes of CA . CB is − circumcentre of ABC lies
4 65 75
inside the ABC
12. AC
Sol. ( a + b ) + (b + c ) + ( a + c ) = 8
Let a + b = ,b + c = ,a + c =
++ =8
+ + = a2 + b2 + c 2 + 3 (ab + bc + ac )
= 21
x3 − 8x 2 + 21x − = 0 where = ( a + b )(b + c )( a + c ) these equations have 3 real roots.
490
27
18
3
7/3
f ( x ) = xe , f ' ( x ) = − ( x − 1) e ,f " ( x ) = e ( x − 2)
−x −x −x
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g'(x) g'’(x)
–1 –2
–1/e
p'(x) p'’(x) 2
+ – + + h (x) = p(x)
, – ,
–1 1 (–1, 0) (1, 0)
0
–2
(0, 3)
q'(x) q'’(x)
(0, 2)
– + – + + – +
, ,
−1 1 –1 0
–1 0 1 1
3 3
(I), (i) (iv), (R)
(II), (i) (iv), (R, S)
(III), (ii) (iv), (P, Q, R)
(IV), (ii) (iii), (P, S)
PART – B
1. 9
Sol. 10! = 28.34.52.7
Number of divisors = 9 5 3 2 = 270 =
2. 0
(h ) = (h )( )
2
Sol. 2
+ k2 − 4 2
+ k 2 − 4h h2 + k 2 − 4k + 16
(
( h + k ) h2 + k 2 − 2h − 2k = 0 circle ) 45o
C1 : x2 + y2 − 2x − 2y = 0 and
C2 : x + y = 0 circumcentre will be mid point of (1, 1)
x+y=0
3. 4
Sol. Sn = 1.3 + 2.22 + 3.33 + 4.24 + ... + upto n – terms
( ) (
Sn = 1.3 + 3.33 + 5.35 + ... + 2.22 + 4.24 + 6.26 + ... )
S1 = 1.3 + 3.33 + 5.35 + ... + upto 10 – terms, S1 =
15
32
5.321 + 1 ( )
58.222 + 8
S2 = 2.22 + 4.24 + 6.26 + ... + upto 10 – terms, S2 =
9
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58.222 + 8
15
S20 = S1 + S2 = 5.321 + 1 + ( )
32 9
75 21 58 22 391
= .3 + .2 +
32 9 288
4. 2.50
3
Sol. 16cos x + 12sin x = 162 + 122 cos ( x − ) , = tan−1 .
4
5. 0.8
x2 y2 1
Sol. Let the equation of the ellipse be 2
+ 2 = 1 where a2 = 82 and b2 = 82 1 −
a b 4
b2
Vertices of the letra recta are ae,
a
2b2
So = 2ae = 4b2 e
a
3 1
= 4 82 = 12 8
4 2
= 0.8
120
6. 1.6
C
Sol. Let A 1, A 2 and M be the centres of the circles
C1,C2 and C respectively. Let the common
tangent through P to C1 and C touch C1 at
B1, C at B 2 and C2 also at B 2 . M
AB 1
A1PB1 = ,sin = 1 1 =
A1P 3 A2 C2
2 2
cos = PB1 = 2 2 = PB2
3 P
PB2 2 2
From triangle MPB2 , tan = = A1
MB2 r
B1
12 2
= = r = 8 . C1
2 2 r
7. –1.25
Sol. 1 − x 0, 1 − x 1 x 1, x 0
3 1 3
Also, log1− x = = (1 − x )
1/2
2 2 2
9 9 −5
= 1− x x = 1− = .
4 4 4
−4x = 5
x = −1.25
8. 6
1
Sol. Clearly x 0 and x
5
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5 log5 5 − log5 x
log5x =
x log5 5 + log5 x
Putting log5 x = t, then equation (1) becomes
1− t
t2 + = 1 t 3 + t 2 − 2t = 0
1+ t
t ( t − 1)( t + 2) = 0 t = 0, 1, − 2
So integral roots of (1) are 1 and 5.
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