Question 1 1.25 / -0
Let S be the set of all positive integers, none of whose prime divisors is greater than 3. Thus 1, 2, 3, 4, 6, 8, 9 and 12 are the smallest elements of S. What is the sum of the reciprocals of the elements of S?
Solution
Sum of the reciprocal of number obtain when product
is expanded, one obtains the sum of the reciprocals of all numbers of the form 2
k ×
where k and
are non-negative integers. This then is precisely the sum asked for in the problem. Each of the factors in the product above is a geometric series, the first equals
= 2 and the second equals
=
. Therefore, the answer is 2 ×
= 3.
Question 2 1.25 / -0
The number of solutions of x2 – 7|x| + 12 = 0 is
Solution
x2 – 7 |x| + 12 = 0 2 – 7x + 12 = 0 2 – 4x – 3x + 12 = 0 2 – (- 7x) + 12 = 0 2 + 4x + 3x + 12 = 0
Question 3 1.25 / -0
How many positive real numbers 'x' satisfy the equation x3 - 3|x| + 2 = 0?
Solution
Condition 1: When x > 0
x
3 - 3x + 2 = 0
(x − 1)(x
2 + x − 2) = 0
(x - 1) (x - 1) (x + 2) = 0
x = 1 and -2
x = -2 is not possible, so x = 1
Condition 2: When x < 0
x
3 - 3|x| + 2 = x
3 + 3x + 2 = 0
at x < 0, f(x) = x
3 + 3x + 2 is monotonically increasing function
at x = 0, f(x) = 2 and at x = -1, f(x) = -2
So, there is one solution between -1 and 0.
Hence, the total number of solutions = 2.
Question 4 1.25 / -0
Let P1 , P2 , P3 , P4 , P5 be the five equally spaced points on the circumference of a circle of radius 1, centered at O. Let R be the set of points in the plane of the circle that are closer to 0 than any of P1 , P2 , P3 , P4 , P5 . Then, R is a
Solution
Points are equidistant from O and P
1 lies on the perpendicular bisector of OP
1 .
So, in the given figure, points on pentagon are equidistant from points P
1 , P
2 , P
3 , P
4 , P
5 and O.
Hence, interior region of pentagon is closed to O.
Question 5 1.25 / -0
The expression ax2 + bx + c, a > 0 is positive for all real x only if
Solution
ax
2 + bx + c =
=
=
For all real x only if
i.e. if b
2 - 4ac < 0
Question 6 1.25 / -0
If the decimal 0.d25d25d25…… is expressible in the form n/27, then d + n must be
Solution
x = 0.d25d25d25.... ....(i)
So, 1000x = d25.d25d25d25... ....(ii)
On solving equation (ii) - (i), we get
1000x - x = d25
x =
=
For 'x' in a form of
, d25 must be divisible by 34 and
is not divisible by divisor of 27.
So, possibility of d is only 9.
So, d = 9, then n =
= 25
Hence, d + n = 25 + 9 = 34
Question 7 1.25 / -0
A student notices that the roots of the equation x2 + bx + a = 0 are each 1 less than the roots of the equation x2 + ax + b = 0. Then, a + b is
Solution
Suppose α and β are the roots of equation x2 + bx + a = 0.2 + ax + b = 0.
Question 8 1.25 / -0
Let ABC be a triangle with
B = 90°. Let AD be the bisector of
A with D on BC. Suppose AC = 6 cm and the area of the triangle ADC is 10 cm
2 . Then, the length of BD (in cm) is equal to
Solution
From angle bisector theorem,
qr = 6p ......(i)
Since area of triangle ADC =
(DC)(AB) = 10
qr = 20, so p =
=
Hence, length BD =
cm
Question 9 1.25 / -0
I carried 1000 kg of watermelon in summer by train. In the beginning, the water content was 99%. By the time I reached the destination, the water content had dropped to 98%. The reduction in the weight of the watermelon was
Solution
Initially concentration of watermelon:
Water + solid = 1000 kg
Weight of water =
= 990 kg
Weight of solid = 10 kg
Suppose y litres of water evaporated.
Then, % of water = 98%
99,000 - 100y = 98,000 - 98y
2y = 1000
y = 500 kg
Hence, reduction in the weight of watermelon = 500 kg
Question 10 1.25 / -0
What will be the area of given shape?
Solution
Area =
× (12 + 25) × 16 +
× 25 × 16
= 296 + 200 = 496 cm
2
Question 11 1.25 / -0
Directions:
Solution
Perimeter of square = ?
Question 12 1.25 / -0
The solution of |x – 1| + |x – 2| + |x – 3| ≥ 6 is:
Solution
Case 1: When x < 1
Then, -x + 1 - x + 2 - x + 3 ≥ 6
-3x + 6 ≥ 6
x ≤ 0 ...(1)
Case 2: When 1 ≤ x < 2
x - 1 - x + 2 - x + 3 ≥ 6
-x ≥ 2
x ≤ -2
So, in case 2, no value of x is possible.
Case 3: When 2 ≤ x < 3
x - 1 + x - 2 - x + 3 ≥ 6
x ≥ 6, but x ∈ [2, 3)
So, in case 3, no value of x is possible.
Case 4: When x ≥ 3
x - 1 + x - 2 + x - 3 ≥ 6
x ≥ 4 ... (2)
Therefore, from equations (1) and (2),
x ∈ (-
, 0] ∪ [4,
)
Question 13 1.25 / -0
Question 14 1.25 / -0
Suppose a, b and c are three distinct real numbers. Let
.
When simplified, P(x) becomes
Solution
Let f(x) = P(x) - 1
then f(a) = 1 + 0 + 0 - 1 = 0
f(b) = 0 + 1 + 0 - 1 = 0 and f(c) = 0 + 0 + 1 - 1 = 0
f(x) is a polynomial of highest degree of 2 and attains same value at 3 different points a, b and c.
i.e. f(x) is an identity and its value is zero
So, P(x) = f(x) + 1 = 1
Hence, the value of P(x) is always 1.
Question 15 1.25 / -0
Consider a triangle drawn on the X - Y plane with its three vertices at (41, 0), (0, 41) and (0, 0), each vertex being represented by its (X, Y) coordinates. What is the number of points with integer coordinates inside the triangle (excluding all the points on the boundary)?
Solution
Number of points from (1, 1) to (39, 1) = 39
Number of points from (2, 1) to (2, 38) = 38
.
.
.
.
Number of points from (39, 1) to (39, 1) = 1
Total points = 1 + 2 + 3 + ………………… + 39
=
= 780
Question 16 1.25 / -0
A boy standing on the footpath tosses a ball straight up and catches it. The driver of a car passing by moving with uniform velocity sees this.
Solution
From the reference frame of the car driver, the path will be like a projectile motion in the opposite direction of the car, (relative motion or reference frame) or we can see it by stopping the car. So, the ball will get a velocity in opposite direction horizontally and the boy provides vertical velocity upwards to the ball, so the path is a projectile motion.
Question 17 1.25 / -0
Two charges +q and -q are placed at a distance 'b' apart as shown in the figure below.
Solution
Answer: along vector
We can understand it by the figure.
Direction of force due to +q will be at 45 degrees anticlockwise from vector A (positive means away from the charge) and direction of force due to -q will be 45 degrees clockwise from vector A (negative means towards the charge).
Vertical components will cancel each other. So, the electric field would be in the direction of vector A.
Question 18 1.25 / -0
The given diagram shows a cubical block completely submerged in water. Which of the following relations among the pressures acting on its four faces (as shown) is true?
Solution
The buoyant force on an object submerged in a fluid is caused by the pressure difference between the top and bottom of the object. To overcome the gravitational force, the buoyant force acts in the upward direction. Now, P4 is the pressure acting in upward direction, P3 is the pressure acting in downward direction and P2 is the pressure acting sideways, which is less than P4 .3 < P2 < P4 .
Question 19 1.25 / -0
The note "Saa" on the Sarod and the Sitar has the same pitch. The property of sound that is most important in distinguishing between the two instruments is
Solution
Waveform is the most important property in distinguishing between the two instruments.
Question 20 1.25 / -0
Two charges +Q and -2Q are located at points A and B on a horizontal line as shown below:
Solution
Electric field at any point due to a point charge q
and
Direction of the electric field is always away from the positive charge. Hence, resultant electric field will be zero at a point which is closer to the smaller charge.
We can say that the resultant electric field will be zero on the left side of the charge Q at point A.
Question 21 1.25 / -0
A hollow pendulum bob filled with water has a small hole at the bottom through which water escapes at a constant rate. Which of the following statements describes the variation of the time period (T) of the pendulum as the water flows out?
Solution
As we know, time period (T) of a pendulum is given by:
Here, l = distance of COM from suspension point.
Now, as water leaks through the hole, the level of water goes down inside the bob and COM of bob goes down.
So, L increases and time period increases.
But when the bob is empty, COM goes to its initial position.
So, L decreases and time period also decreases.
Question 22 1.25 / -0
Which of the following colours cannot be distinguished by a person suffering from colour blindness?
Solution
Colour blindness is a defect of the eye due to which a person is not able to distinguish between certain colours. 99% of the total colour blind people are unable to distinguish between red and green colours.
Question 23 1.25 / -0
Two identical blocks of metal are at 20°C and 80°C, respectively. The specific heat of the material of the two blocks increases with temperature. Which of the following is true about the final temperature Tf when the two blocks are bought into contact (assuming that no heat is lost to the surroundings)?
Solution
As it is given that specific heat S increases with temperature, S at 80°C would be greater than S at 20°C.
Question 24 1.25 / -0
Seven resistances are connected as shown in the given figure. The effective resistance between the points A and B is
Solution
Here in branch AED, resistances across AE and ED are in series. So, resistance across AED = 2
Now, this resistance is in parallel with branch AD. So, resistance across AD =
Similarly, resistance across ADC =
+ 1 (as
and 1
are in series, and the combination is in parallel with AC.)
Thus, resistance across ADC =
Similarly, resistance across ACB =
(As
and 1
are in series.)
Resistance across AB =
Question 25 1.25 / -0
A simple pendulum oscillates freely between points A and B.
Solution
Let 'h' be the height of point A from the equilibrium position at which velocity of the particle becomes zero.
Let 'H' be the height of the point D above the equilibrium position.
Using conservation of mechanical energy,
Total energy at point A = Total energy at point D
U
A + K
A = U
D + K
D ⇒ mgh + 0 = mgH + 0
h = H
Hence, point D will lie on the straight line AB.
Question 26 1.25 / -0
In an arrangement of resistances shown in the diagram, the potential difference between B and D will be zero, when the unknown resistance X is
Solution
For the potential difference across B and D to be zero,
Equivalent resistance of AB = 16
Equivalent resistance of AD = 4
Equivalent resistance of DC = 0.5
X = 2 ohms
Question 27 1.25 / -0
The mass of body A is twice that of B, and the speed of A is half that of B. The kinetic energies of A and B are in the ratio
Solution
Let the mass of B be m.
Mass of A = 2 m
Let the speed of B be v and speed of A be v/2.
K. E. of B =
mv
2 K. E. of A =
× 2 m ×
= m
= 1/2
KE of A : KE of B = 1 : 2
Question 28 1.25 / -0
We sit in the room with windows open. Then,
Solution
We sit in the room with windows open. The air pressure is nearly the same on the floor, the walls and the ceiling because the height of the room is very small as compared to the height of the atmosphere.
Question 29 1.25 / -0
A 750 W motor drives a pump which lifts 300 litres of water per minute to a height of 6 metres. The efficiency of the motor is nearly (take acceleration due to gravity to be 10 m/s2 )
Solution
Efficiency of the pump,
%
Question 30 1.25 / -0
The figure below shows a portion of an electric circuit with the currents in amperes and their directions. The magnitude and direction of the current in the portion PQ is
Solution
Using Kirchoff's junction law at point A, current in path AB is 10 A.
Current in path BC is 6 A. Hence, current in path BD is 4 A.
Current in path DQ is 3 A. So, we can say that the current which flows from Q to P is 6 A.
Question 31 1.25 / -0
The IUPAC name of –C2 H5 OH is
Solution
The IUPAC name of –C2 H5 OH alcohol is ethanol.
Question 32 1.25 / -0
Which of the following options was compared with the dry fruits in a spherical Christmas pudding in the Thomson's model of atom?
Solution
Electron was compared with the dry fruits in a spherical Christmas pudding in the Thomson's model of atom.
Question 33 1.25 / -0
Order of hybridisation (of carbon) in methane, ethylene and acetylene will be, respectively
Solution
In structure of methane there is no double bond, therefore form sp3 structure on hybridisation. Ethylene contains one double bond in its structure therefore form sp2 structure on hybridisation and acetylene contain one triple bond therefore it form sp type structure.
Question 34 1.25 / -0
The electronic configuration of 1s2 , 2s2 2p6 , 3s2 , 3p3 corresponds to
Solution
The electronic configuration of 1s2 , 2s2 2p6 , 3s2 , 3p3 corresponds to element with atomin number 15. So the element is phosphorus.
Question 35 1.25 / -0
The electronic configuration of a dipositive ion M is 2, 8, 14 and its atomic weight is 56. The number of neutrons in the nucleus would be ____________.
Solution
M2+ has total number of electrons = 2 + 8 + 14 = 24
Question 36 1.25 / -0
The geometry & the dipole moment of H2 S is
Solution
Due to the presence of 2 bond pair and two lone pairs, H2 S has angular and has non-zero dipole moment.
Question 37 1.25 / -0
The value of univeral gas constant 'R' depends only on the
Solution
The value of univeral gas constant 'R' depends only on the units of the measurements.
Question 38 1.25 / -0
A gas occupies 800 cm3 under a pressure of 760 mm Hg. Under what pressure will the volume of the gas be reduced by 20% of its original volume? (Temperature remains constant.)
Solution
× 800 = 160
New volume V
2 = 800 – 160 = 640 cm
3 At a constant temperature:
P
1 V
1 = P
2 V
2 (Boyle's law)
800
760 = P
2 640
P
2 = 950 mm Hg
Question 39 1.25 / -0
What is the colour of the coating formed on copper when it reacts with moist carbon dioxide?
Solution
The surfaces of many metals become either dull or are slowly damaged when those are kept in the open for a long period. This is called corrosion. For example, copper reacts with moist carbon dioxide and acquires a green coating due to the formation of basic copper carbonate.
Question 40 1.25 / -0
The equilibrium constant for the reaction NH
4 NO
2 (s)
N
2 (g) + 2H
2 O(g) is given by:
Solution
Because for equillibrium constant concentration of solids are considered one.
Question 41 1.25 / -0
What is molarity of K+ in aqueous solution that contains 17.4 ppm of K2 SO4 (174 g mol-1 )?
Solution
17.4 ppm = 17.4 mg K
2 SO
4 /L of solution = 0.0174 g/L
Volume of the solution:
Molality of K
+ ion = Number of moles of K
+ x volume of solution:
= 2 × .0001 = .0002 or 2 × 10
-4 M
Question 42 1.25 / -0
Which one the following sets of ions represents the collection of isoelectronic species?
Solution
isoelectronic species have equal number of electrons.+ (atomic number 19): 182+ (atomic number 20): 183+ (atomic number 21): 18- (atomic number 17): 18+ , Ca2+ , Sc3+ , Cl- are isoelectronic species.
Question 43 1.25 / -0
How many
and
bonds are present in toluene?
Solution
Toluene contains 3
bonds and 15
bonds.
Question 44 1.25 / -0
Which of the following metals will not be able to displace lead from its salt solution?
Solution
A more reactive metal can displace a less reactive metal from its salt solution. The reactivity series of metals is given below:
K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Hg > Ag > Au
Most reactive
Least reactive
Question 45 1.25 / -0
Excitation energy of a hydrogen like ion in its first excitation state is 40.8 eV. The energy needed to remove the electron from the ion in the ground state is:
Solution
The excitation energy in the first excited state is
E = RhcZ
2 = (13.6 eV) × Z
2 ×
∴ 40.8 = 13.6 × Z
2 ×
⇒ Z = 2
So, the ion in problem is He
+ . The energy of the ion in the ground state is
E = -
= - 13.6 × 4 = -54.4 eV
Hence, 54.4 eV is required to remove the electron from the ion.
Question 46 1.25 / -0
The plasma resembles in its composition with the filtrate found in the Bowman's capsule except for the presence of
Solution
The plasma resembles in its composition with the filtrate found in the Bowman's capsule except for the presence of proteins.
Question 47 1.25 / -0
Which of the following is the master gland of the body?
Solution
Pituitary gland is the master gland of the body.
Question 48 1.25 / -0
Which of the following diseases cannot be prevented by vaccines?
Solution
These diseases cannot be prevented by vaccination.
Question 49 1.25 / -0
What is the gene ratio of F2 generation in a monohybrid cross?
Solution
Considering the gene for tallness of a plant, the monohybrid cross can be shown as follows:
Thus, the correct answer is (2).
Question 50 1.25 / -0
Identify from the following, the disease that enters the human body through mosquito bite and affects the brain.
Solution
It spreads through a mosquito bite and affects the brain.
Question 51 1.25 / -0
A disease transmitted by sexual contact is
Solution
A disease transmitted by sexual contact is AIDS. Its virus gets transmitted through contact with infected blood, semen or vaginal fluids. Its symptoms are weight loss, fever, fatigue and recurrent infections.
Question 52 1.25 / -0
An individual has O blood group. His/her blood sample
Solution
If the blood cells clump (agglutinate), the antibody has bound to the appropriate antigen on the cells. Blood group O does not clump when either antiserum A or antiserum B is added because it has no antigens present on its surface.
Question 53 1.25 / -0
Which base is present in RNA but not in DNA?
Solution
Thymine is present in DNA and absent in RNA. Uracil is present in RNA and absent in DNA.
Question 54 1.25 / -0
Which of the following is/are the smallest in size?
Solution
Viruses are the smallest. Specific kinds of viruses range in size from a few dozen nanometres up to about 1,000 nanometres or 1 micrometre.
Question 55 1.25 / -0
The connecting link between a mother's blood and foetal blood is termed as
Solution
An embryo gets nutrition from the mother's blood with the help of a special tissue called placenta. This is a disc which lies in the uterine wall and provides a large surface area for glucose and oxygen to pass from the mother to the embryo for its development. Also, it helps in the removal of waste material from the embryo into the mother's blood. So, the placenta acts as a connecting link between a mother's blood and foetal blood.
Question 56 1.25 / -0
What is the scientific name of housefly?
Solution
The housefly, Musca domestica, is a fly of the suborder Cyclorrhapha. It is believed to have evolved in the Cenozoic era, possibly in the Middle East, and has spread all over the world. It is the most common fly species found in habitations.
Question 57 1.25 / -0
Animals like tigers, wild buffaloes, barasingha, etc. are categorised as
Solution
Tigers, wild buffaloes, barasingha, etc. are endangered species.
Question 58 1.25 / -0
Dietary fibres are composed of
Solution
Fibre consists of non-starch polysaccharides, such as cellulose, dextrins, inulin, lignin, chitins, pectins, beta-glucans, waxes, and oligosaccharides.
Question 59 1.25 / -0
The structural adaptation in flowers that prevents self pollination is known as
Solution
The structural adaptation in flowers that prevents self pollination is known as herkogamy.
Question 60 1.25 / -0
The avian heart is __________.
Solution
Aves (birds) are warm blooded animals and have four chambered heart, e.g. ostrich, duck, etc. Mammals also have four chambered heart.
Question 61 1.25 / -0
Let f(x) = 1 + x + x2 + x3 + x4 + x5 . What is the remainder when f(x12 ) is divided by f(x)?
Solution
f(x) = x5 + x4 + x3 + x2 + x + 15 + x4 + ... + 1 = (x6 - 1)/(x - 1)12 ) = (x72 - 1)/(x12 - 1)12 ) - 6 = (x60 - 1) + (x48 - 1) + (x36 - 1) + (x24 - 1) + (x12 - 1)mk - 1 is divisible by xk - 1, thus, all terms on the right side are divisible by x6 - 1, and hence by f(x). Thus, the remainder is 6.
Question 62 1.25 / -0
Let loga b = 4 and logc d = 2, where a, b, c and d are natural numbers. Given that b - d = 7, the value of c - a is
Solution
logb a = 4 ⇒ b = a4 d c = 2 ⇒ d = c2 4 - c2 = (a2 + c)(a2 - c) = 7 = 7 × 12 + c and a2 - c are also natural numbers.2 + c = 7 and a2 - c = 1 ⇒ a = 2 and c = 3
Question 63 1.25 / -0
If a
2 = by + cz, b
2 = cz + ax and c
2 = ax + by, then
is equal to
Solution
Given that a
2 = by + cz ... (i), b
2 = cz + ax ... (ii) and c
2 = ax + by ... (iii)
Now,
From (i), (ii) and (iii) we get,
Let us assume some value for a, b, c, x, y and z, i.e. 2, 2, 2, 1, 1 and 1, which satisfy the given condition of a
2 = by + cz and b
2 = cz + ax.
Putting the value a, b, c, x, y and z in
, we get
Question 64 1.25 / -0
A solid cube with 6 m side is given, having a hole exactly at its centre with radius of 2 m. Find the surface area of the remaining cube.
Solution
Area of cube = 216 cm
2 Area of cylindrical hole = 2
rh
= 2 × 3.14 × 2 × 6
= 75.36
Area of circles = 2 × 22/7 × 4 = 25.14 cm
2 Area of the remaining cube = 216 + 75.36 - 25.14 = 266.22 cm
2
Question 65 1.25 / -0
If a rectangle and an equilateral triangle with equal area are inscribed in a circle of radius 2 units, then one of the dimensions of the rectangle is
Solution
Let length and breadth of the rectangle respectively be 'x' units and 'y' units, and side of the equilateral triangle be 'a' units.
A.T.Q.
a
2 = xy
Or x
2 y
2 =
a
4 ...(1)
Now, Diagonal of a rectangle = Diameter of a circle
∴
= 4
x
2 + y
2 = 16 ...(2)
Now,
of height of the triangle = Radius of the circle
a = 2
a =
...(3)
From equations (1) and (3), we get
x
2 y
2 = 27
Or y
2 =
...(4)
Using equations (2) and (4), we get
x
2 +
= 16
Or x
4 - 16x
2 + 27 = 0
Or x =
units
Question 66 1.25 / -0
Two particles A and B, initially at rest, move towards each other under a mutual force of attraction. At the instant when the speed of A is V and that of B is 2V, the speed of the centre of mass of the system is
Solution
Since no external force acts on the system, the centre of mass will remain at rest. Hence, the correct choice is (1).
Question 67 1.25 / -0
A spring balance 'A' reads 2 kg with a block of mass 'm' suspended from it. Another balance 'B' reads 3 kg when a beaker with a liquid is put on its pan. The two balances are now so arranged that the hanging mass 'm' is fully immersed inside the liquid in the beaker as shown in the figure. In this situation,
Solution
When the block is immersed in the liquid, buoyant force will act in upward direction hence, A will read lesser than 2 kg.
Question 68 1.25 / -0
A metal rod joins three iron balls having different temperatures as shown below:
What will be the direction of the flow of heat?
Solution
The direction of the flow of heat is from B to A and B to C. This is because the transfer of heat energy takes place from the body at higher temperature to the body at lower temperature in contact with each other till the temperatures of the two bodies become equal. This process of energy transfer is known as conduction.
Question 69 1.25 / -0
In a military training exercise, three teams are stationed at points A, B and C, as shown below, with a hillock between teams A and C. Team A sends a light signal to B, which has to reflect it to team C, so that all the three teams start the exercise simultaneously. What should be the angle
of the reflecting mirror, held by team B?
Solution
Applying the laws of reflection, for the mirror at B,
Angle of reflection = Angle of incidence = 30°
Hence,
= 90° – 60° = 30°
Question 70 1.25 / -0
Two springs, of force constants k
1 and k
2 , are connected to a mass m as shown. The frequency of oscillation of the mass is f. If both k
1 and k
2 are made four times their original values, the frequency of oscillation becomes
Solution
Frequency of the oscillation of the spring block system is:
; where m is the mass of the block and k is the spring constant.
The springs are connected in parallel, so the equivalent spring constant is k = k
1 + k
2. So, the frequency of oscillation:
When k
1 and k
2 are made four times, then frequency of oscillation is:
Hence, we can conclude that f' = 2f.
Question 71 1.25 / -0
1, 3-Butadiene on reaction with HBr at 313 K gives the formation of _______ as the major product.
Question 72 1.25 / -0
Ethyl chloride on reduction with LiAlH4 gives compound 'X' as a major product. 'X' on chlorination with one mole of Cl2 in the presence of light at ordinary temperature gives 'Y'. What is 'Y'?
Question 73 1.25 / -0
Benzene when treated with
2 in the presence of sunlight, primarily gives
Question 74 1.25 / -0
What is the ratio of the occurrence of Cl - 37 and Cl - 35 isotopes of chlorine in nature?
Solution
The average atomic mass of Cl-35 is 35.5 u. Let the %age of Cl-35 be x% and %age of Cl-37 be (100 - x)%. Then, %age of both isotopes in nature is:
= 35.5
x = 75%
∴ 100 - x = 100 - 75 = 25%
Hence, CI
35 is 75% and CI
37 is 25%
It is clear from the above calculation, the %age abundance of Cl-37 is 25% and that of Cl-35 is 75%. Thus, ratio of both isotopes is: 1 : 3.
Question 75 1.25 / -0
The nucleus 6 C12 absorbs an energetic neutron and emits a beta particle (β). The resulting nucleus is
Solution
Any nuclear reaction should follow conservation of charge, mass number, linear momentum, angular momentum and spin.
Following Nuclear reaction will take place
is the antineutrino.
Question 76 1.25 / -0
The nucleolus, golgi complex and ER reform in which of the following phases of the cell cycle?
Solution
Nuclear envelope assembles around the chromosome clusters and nucleolus, golgi complex and ER reform in telophase.
Question 77 1.25 / -0
Match the following:
Column A Column B P. Translation i. Production of ribosomes Q. Nucleolus ii. Ribosomes R. Crick iii. DNA polymerase S. Replication iv. Central dogma
Solution
Ribosome is the organelle where translation occurs. Ribosomes are produced in the nucleolus. Francis Crick discovered Central dogma. Replication of DNA is brought about by DNA polymerase.
Question 78 1.25 / -0
When do two chromatids of a chromosome separate from each other?
Solution
The poleward movement of chromatids of the chromosomes takes place during this phase.
Question 79 1.25 / -0
What is the triangular cartilaginous structure located between the tongue and the trachea called?
Solution
The larynx, or voice box, is a triangular cartilaginous structure located between the tongue and the trachea. It is protected anteriorly by the thyroid cartilage.
Question 80 1.25 / -0
What do you mean by Residual volume?
Solution
Residual volume is the amount of air remaining in the lungs after a forced exhalation.
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