JEE Main 2023 (Online) 30th January Morning Shift
Paper was held on Mon, Jan 30, 2023 3:30 AM
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Chemistry

1

To inhibit the growth of tumours, identify the compounds used from the following :

A. EDTA

B. Coordination Compounds of Pt

C. D - Penicillamine

D. Cis - Platin

Choose the correct answer from the option given below :

2

The major products 'A' and 'B', respectively, are

JEE Main 2023 (Online) 30th January Morning Shift Chemistry - Hydrocarbons Question 51 English

3

In the wet tests for identification of various cations by precipitation, which transition element cation doesn't belong to group IV in qualitative inorganic analysis?

4

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : Ketoses give Seliwanoff's test faster than Aldoses.

Reason (R) : Ketoses undergo $$\beta$$-elimination followed by formation of furfural.

In the light of the above statements, choose the correct answer from the options given below :

5

What is the correct order of acidity of the protons marked $$\mathrm{A}-\mathrm{D}$$ in the given compounds ?

JEE Main 2023 (Online) 30th January Morning Shift Chemistry - Aldehydes, Ketones and Carboxylic Acids Question 66 English

6

Which of the following is correct order of ligand field strength?

7

Which of the following compounds would give the following set of qualitative analysis ?

(i) Fehling's Test : Positive

(ii) Na fusion extract upon treatment with sodium nitroprusside gives a blood red colour but not prussian blue.

8

During the qualitative analysis of $$\mathrm{SO}_{3}^{2-}$$ using dilute $$\mathrm{H}_{2} \mathrm{SO}_{4}, \mathrm{SO}_{2}$$ gas is evolved which turns $$\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$$ solution (acidified with dilute $$\mathrm{H}_{2} \mathrm{SO}_{4}$$) :

9

For $$\mathrm{OF}_{2}$$ molecule consider the following :

A. Number of lone pairs on oxygen is 2 .

B. FOF angle is less than $$104.5^{\circ}$$.

C. Oxidation state of $$\mathrm{O}$$ is $$-2$$.

D. Molecule is bent '$$\mathrm{V}$$' shaped.

E. Molecular geometry is linear.

correct options are:

10

Match List I with List II

List I List II
A. JEE Main 2023 (Online) 30th January Morning Shift Chemistry - Haloalkanes and Haloarenes Question 52 English 1 I. Fittig reaction
B. JEE Main 2023 (Online) 30th January Morning Shift Chemistry - Haloalkanes and Haloarenes Question 52 English 2 II. Wurtz Fittig reaction
C. JEE Main 2023 (Online) 30th January Morning Shift Chemistry - Haloalkanes and Haloarenes Question 52 English 3 III. Finkelstein reaction
D. $$\mathrm{C_5H_5C1+NaI\to C_2H_5I+NaCl}$$ IV. Sandemyer reaction

Choose the correct answer from the options given below :

11

Benzyl isocyanide can be obtained by :

A. JEE Main 2023 (Online) 30th January Morning Shift Chemistry - Compounds Containing Nitrogen Question 67 English 1

B. JEE Main 2023 (Online) 30th January Morning Shift Chemistry - Compounds Containing Nitrogen Question 67 English 2

C. JEE Main 2023 (Online) 30th January Morning Shift Chemistry - Compounds Containing Nitrogen Question 67 English 3

D. JEE Main 2023 (Online) 30th January Morning Shift Chemistry - Compounds Containing Nitrogen Question 67 English 4

Choose the correct answer from the options given below :

12

Match List I with List II

List I
(Atomic number)
List II
(Block of periodic table)
A. 37 I. p-block
B. 78 II. d-block
C. 52 III. f-block
D. 65 IV. s-block

Choose the correct answer from the options given below :

13

Match List I with List II

List I
(molecules/ions)
List II
(No. of lone pairs of e$$^-$$ on central atom)
A. $$\mathrm{IF_7}$$ I. Three
B. $$\mathrm{ICl}$$$$_4^ - $$ II. One
C. $$\mathrm{XeF_6}$$ III. Two
D. $$\mathrm{XeF_2}$$ IV. Zero

Choose the correct answer from the options given below :

14

Some amount of dichloromethane $$\left(\mathrm{CH}_{2} \mathrm{Cl}_{2}\right)$$ is added to $$671.141 \mathrm{~mL}$$ of chloroform $$\left(\mathrm{CHCl}_{3}\right)$$ to prepare $$2.6 \times 10^{-3} \mathrm{M}$$ solution of $$\mathrm{CH}_{2} \mathrm{Cl}_{2}(\mathrm{DCM})$$. The concentration of $$\mathrm{DCM}$$ is ___________ ppm (by mass).

Given :

atomic mass : C = 12

H = 1

Cl = 35.5

density of $$\mathrm{CHCl}_{3}=1.49 \mathrm{~g} \mathrm{~cm}^{-3}$$

15

If compound A reacts with B following first order kinetics with rate constant $$2.011 \times 10^{-3} \mathrm{~s}^{-1}$$. The time taken by $$\mathrm{A}$$ (in seconds) to reduce from $$7 \mathrm{~g}$$ to $$2 \mathrm{~g}$$ will be ___________. (Nearest Integer)

$$[\log 5=0.698, \log 7=0.845, \log 2=0.301]$$

16

$$600 \mathrm{~mL}$$ of $$0.01~\mathrm{M} ~\mathrm{HCl}$$ is mixed with $$400 \mathrm{~mL}$$ of $$0.01~\mathrm{M} ~\mathrm{H}_{2} \mathrm{SO}_{4}$$. The $$\mathrm{pH}$$ of the mixture is ___________ $$\times 10^{-2}$$. (Nearest integer)

[Given $$\log 2=0.30$$

$$\log 3=0.48$$

$$\log 5=0.69$$

$$\log 7=0.84$$

$$\log 11=1.04]$$

17

When 2 litre of ideal gas expands isothermally into vacuum to a total volume of 6 litre, the change in internal energy is ____________ J. (Nearest integer)

18

Consider the cell

$$\mathrm{Pt}_{(\mathrm{s})}\left|\mathrm{H}_{2}(\mathrm{~g}, 1 \mathrm{~atm})\right| \mathrm{H}^{+}(\mathrm{aq}, 1 \mathrm{M})|| \mathrm{Fe}^{3+}(\mathrm{aq}), \mathrm{Fe}^{2+}(\mathrm{aq}) \mid \operatorname{Pt}(\mathrm{s})$$

When the potential of the cell is $$0.712 \mathrm{~V}$$ at $$298 \mathrm{~K}$$, the ratio $$\left[\mathrm{Fe}^{2+}\right] /\left[\mathrm{Fe}^{3+}\right]$$ is _____________. (Nearest integer)

Given : $$\mathrm{Fe}^{3+}+\mathrm{e}^{-}=\mathrm{Fe}^{2+}, \mathrm{E}^{\theta} \mathrm{Fe}^{3+}, \mathrm{Fe}^{2+} \mid \mathrm{Pt}=0.771$$

$$ \frac{2.303 \mathrm{RT}}{\mathrm{F}}=0.06 \mathrm{~V} $$

19

A trisubstituted compound '$$\mathrm{A}$$', $$\mathrm{C}_{10} \mathrm{H}_{12} \mathrm{O}_{2}$$ gives neutral $$\mathrm{FeCl}_{3}$$ test positive. Treatment of compound 'A' with $$\mathrm{NaOH}$$ and $$\mathrm{CH}_{3} \mathrm{Br}$$ gives $$\mathrm{C}_{11} \mathrm{H}_{14} \mathrm{O}_{2}$$, with hydroiodic acid gives methyl iodide and with hot conc. $$\mathrm{NaOH}$$ gives a compound $$\mathrm{B}, \mathrm{C}_{10} \mathrm{H}_{12} \mathrm{O}_{2}$$. Compound 'A' also decolorises alkaline $$\mathrm{KMnO}_{4}$$. The number of $$\pi$$ bond/s present in the compound '$$\mathrm{A}$$' is _____________.

20

The number of electrons involved in the reduction of permanganate to manganese dioxide in acidic medium is _____________.

21

A solution containing $$2 \mathrm{~g}$$ of a non-volatile solute in $$20 \mathrm{~g}$$ of water boils at $$373.52 \mathrm{~K}$$. The molecular mass of the solute is ___________ $$\mathrm{g} ~\mathrm{mol}^{-1}$$. (Nearest integer)

Given, water boils at $$373 \mathrm{~K}, \mathrm{~K}_{\mathrm{b}}$$ for water $$=0.52 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$$

22

The energy of one mole of photons of radiation of frequency $$2 \times 10^{12} \mathrm{~Hz}$$ in $$\mathrm{J} ~\mathrm{mol}^{-1}$$ is ___________. (Nearest integer)

[Given : $$\mathrm{h}=6.626 \times 10^{-34} ~\mathrm{Js}$$

$$\mathrm{N}_{\mathrm{A}}=6.022 \times 10^{23} \mathrm{~mol}^{-1}$$]

Mathematics

1

Let the solution curve $$y=y(x)$$ of the differential equation

$$ \frac{\mathrm{d} y}{\mathrm{~d} x}-\frac{3 x^{5} \tan ^{-1}\left(x^{3}\right)}{\left(1+x^{6}\right)^{3 / 2}} y=2 x \exp \left\{\frac{x^{3}-\tan ^{-1} x^{3}}{\sqrt{\left(1+x^{6}\right)}}\right\} \text { pass through the origin. Then } y(1) \text { is equal to : } $$

2

The minimum number of elements that must be added to the relation $$ \mathrm{R}=\{(\mathrm{a}, \mathrm{b}),(\mathrm{b}, \mathrm{c})\}$$ on the set $$\{a, b, c\}$$ so that it becomes symmetric and transitive is :

3

Let the system of linear equations

$$x+y+kz=2$$

$$2x+3y-z=1$$

$$3x+4y+2z=k$$

have infinitely many solutions. Then the system

$$(k+1)x+(2k-1)y=7$$

$$(2k+1)x+(k+5)y=10$$

has :

4

If [t] denotes the greatest integer $$\le \mathrm{t}$$, then the value of $${{3(e - 1)} \over e}\int\limits_1^2 {{x^2}{e^{[x] + [{x^3}]}}dx} $$ is :

5

If the coefficient of $$x^{15}$$ in the expansion of $$\left(\mathrm{a} x^{3}+\frac{1}{\mathrm{~b} x^{1 / 3}}\right)^{15}$$ is equal to the coefficient of $$x^{-15}$$ in the expansion of $$\left(a x^{1 / 3}-\frac{1}{b x^{3}}\right)^{15}$$, where $$a$$ and $$b$$ are positive real numbers, then for each such ordered pair $$(\mathrm{a}, \mathrm{b})$$ :

6

Suppose $$f: \mathbb{R} \rightarrow(0, \infty)$$ be a differentiable function such that $$5 f(x+y)=f(x) \cdot f(y), \forall x, y \in \mathbb{R}$$. If $$f(3)=320$$, then $$\sum_\limits{n=0}^{5} f(n)$$ is equal to :

7

If the solution of the equation $$\log _{\cos x} \cot x+4 \log _{\sin x} \tan x=1, x \in\left(0, \frac{\pi}{2}\right)$$, is $$\sin ^{-1}\left(\frac{\alpha+\sqrt{\beta}}{2}\right)$$, where $$\alpha$$, $$\beta$$ are integers, then $$\alpha+\beta$$ is equal to :

8

If $$\tan 15^\circ + {1 \over {\tan 75^\circ }} + {1 \over {\tan 105^\circ }} + \tan 195^\circ = 2a$$, then the value of $$\left( {a + {1 \over a}} \right)$$ is :

9

Let a unit vector $$\widehat{O P}$$ make angles $$\alpha, \beta, \gamma$$ with the positive directions of the co-ordinate axes $$\mathrm{OX}$$, $$\mathrm{OY}, \mathrm{OZ}$$ respectively, where $$\beta \in\left(0, \frac{\pi}{2}\right)$$. If $$\widehat{\mathrm{OP}}$$ is perpendicular to the plane through points $$(1,2,3),(2,3,4)$$ and $$(1,5,7)$$, then which one of the following is true?

10

If an unbiased die, marked with $$-2,-1,0,1,2,3$$ on its faces, is thrown five times, then the probability that the product of the outcomes is positive, is :

11

$$\lim_\limits{x \rightarrow 0} \frac{48}{x^{4}} \int_\limits{0}^{x} \frac{t^{3}}{t^{6}+1} \mathrm{~d} t$$ is equal to ___________.

12

Number of 4-digit numbers (the repetition of digits is allowed) which are made using the digits 1, 2, 3 and 5, and are divisible by 15, is equal to ___________.

13

Let $$z=1+i$$ and $$z_{1}=\frac{1+i \bar{z}}{\bar{z}(1-z)+\frac{1}{z}}$$. Then $$\frac{12}{\pi} \arg \left(z_{1}\right)$$ is equal to __________.

14

Let $$\alpha$$ be the area of the larger region bounded by the curve $$y^{2}=8 x$$ and the lines $$y=x$$ and $$x=2$$, which lies in the first quadrant. Then the value of $$3 \alpha$$ is equal to ___________.

15

Let $$S=\{1,2,3,4,5,6\}$$. Then the number of one-one functions $$f: \mathrm{S} \rightarrow \mathrm{P}(\mathrm{S})$$, where $$\mathrm{P}(\mathrm{S})$$ denote the power set of $$\mathrm{S}$$, such that $$f(n) \subset f(\mathrm{~m})$$ where $$n < m$$ is ____________.

16

Let $$f^{1}(x)=\frac{3 x+2}{2 x+3}, x \in \mathbf{R}-\left\{\frac{-3}{2}\right\}$$ For $$\mathrm{n} \geq 2$$, define $$f^{\mathrm{n}}(x)=f^{1} \mathrm{o} f^{\mathrm{n}-1}(x)$$. If $$f^{5}(x)=\frac{\mathrm{a} x+\mathrm{b}}{\mathrm{b} x+\mathrm{a}}, \operatorname{gcd}(\mathrm{a}, \mathrm{b})=1$$, then $$\mathrm{a}+\mathrm{b}$$ is equal to ____________.

17

The mean and variance of 7 observations are 8 and 16 respectively. If one observation 14 is omitted and a and b are respectively mean and variance of remaining 6 observation, then $$\mathrm{a+3 b-5}$$ is equal to ___________.

Physics

1

A massless square loop, of wire of resistance $$10 \Omega$$, supporting a mass of $$1 \mathrm{~g}$$, hangs vertically with one of its sides in a uniform magnetic field of $$10^{3} \mathrm{G}$$, directed outwards in the shaded region. A dc voltage $$\mathrm{V}$$ is applied to the loop. For what value of $$\mathrm{V}$$, the magnetic force will exactly balance the weight of the supporting mass of $$1 \mathrm{~g}$$ ?

(If sides of the loop $$=10 \mathrm{~cm}, \mathrm{~g}=10 \mathrm{~ms}^{-2}$$)

JEE Main 2023 (Online) 30th January Morning Shift Physics - Magnetic Effect of Current Question 66 English

2

The height of liquid column raised in a capillary tube of certain radius when dipped in liquid A vertically is, $$5 \mathrm{~cm}$$. If the tube is dipped in a similar manner in another liquid $$\mathrm{B}$$ of surface tension and density double the values of liquid $$\mathrm{A}$$, the height of liquid column raised in liquid $$\mathrm{B}$$ would be __________ m.

3

A small object at rest, absorbs a light pulse of power $$20 \mathrm{~mW}$$ and duration $$300 \mathrm{~ns}$$. Assuming speed of light as $$3 \times 10^{8} \mathrm{~m} / \mathrm{s}$$, the momentum of the object becomes equal to :

4

Choose the correct relationship between Poisson ratio $$(\sigma)$$, bulk modulus (K) and modulus of rigidity $$(\eta)$$ of a given solid object :

5

The pressure $$(\mathrm{P})$$ and temperature ($$\mathrm{T})$$ relationship of an ideal gas obeys the equation $$\mathrm{PT}^{2}=$$ constant. The volume expansion coefficient of the gas will be :

6

The output waveform of the given logical circuit for the following inputs A and B as shown below, is :

JEE Main 2023 (Online) 30th January Morning Shift Physics - Semiconductor Question 52 English

7

As per the given figure, a small ball P slides down the quadrant of a circle and hits the other ball Q of equal mass which is initially at rest. Neglecting the effect of friction and assume the collision to be elastic, the velocity of ball Q after collision will be :

(g = 10 m/s2)

JEE Main 2023 (Online) 30th January Morning Shift Physics - Center of Mass and Collision Question 23 English

8

The charge flowing in a conductor changes with time as $$\mathrm{Q}(\mathrm{t})=\alpha \mathrm{t}-\beta \mathrm{t}^{2}+\gamma \mathrm{t}^{3}$$. Where $$\alpha, \beta$$ and $$\gamma$$ are constants. Minimum value of current is :

9

Heat is given to an ideal gas in an isothermal process.

A. Internal energy of the gas will decrease.

B. Internal energy of the gas will increase.

C. Internal energy of the gas will not change.

D. The gas will do positive work.

E. The gas will do negative work.

Choose the correct answer from the options given below :

10

Electric field in a certain region is given by $$\overrightarrow{\mathrm{E}}=\left(\frac{\mathrm{A}}{x^{2}} \hat{i}+\frac{\mathrm{B}}{y^{3}} \hat{j}\right) \text {. The } \mathrm{SI} \text { unit of } \mathrm{A} \text { and } \mathrm{B}$$ are :

11

Two isolated metallic solid spheres of radii $$\mathrm{R}$$ and $$2 \mathrm{R}$$ are charged such that both have same charge density $$\sigma$$. The spheres are then connected by a thin conducting wire. If the new charge density of the bigger sphere is $$\sigma^{\prime}$$. The ratio $$\frac{\sigma^{\prime}}{\sigma}$$ is :

12

Speed of an electron in Bohr's $$7^{\text {th }}$$ orbit for Hydrogen atom is $$3.6 \times 10^{6} \mathrm{~m} / \mathrm{s}$$. The corresponding speed of the electron in $$3^{\text {rd }}$$ orbit, in $$\mathrm{m} / \mathrm{s}$$ is :

13

The magnetic moments associated with two closely wound circular coils $$\mathrm{A}$$ and $$\mathrm{B}$$ of radius $$\mathrm{r}_{\mathrm{A}}=10$$ $$\mathrm{cm}$$ and $$\mathrm{r}_{\mathrm{B}}=20 \mathrm{~cm}$$ respectively are equal if : (Where $$\mathrm{N}_{\mathrm{A}}, \mathrm{I}_{\mathrm{A}}$$ and $$\mathrm{N}_{\mathrm{B}}, \mathrm{I}_{\mathrm{B}}$$ are number of turn and current of $$\mathrm{A}$$ and $$\mathrm{B}$$ respectively)

14

The figure represents the momentum time ($$\mathrm{p}-\mathrm{t}$$) curve for a particle moving along an axis under the influence of the force. Identify the regions on the graph where the magnitude of the force is maximum and minimum respectively?

If $$\left(t_{3}-t_{2}\right) < t_{1}$$

JEE Main 2023 (Online) 30th January Morning Shift Physics - Center of Mass and Collision Question 22 English

15

If the gravitational field in the space is given as $$\left(-\frac{K}{r^{2}}\right)$$. Taking the reference point to be at $$\mathrm{r}=2 \mathrm{~cm}$$ with gravitational potential $$\mathrm{V}=10 \mathrm{~J} / \mathrm{kg}$$. Find the gravitational potential at $$\mathrm{r}=3 \mathrm{~cm}$$ in SI unit (Given, that $$\mathrm{K}=6 \mathrm{~Jcm} / \mathrm{kg}$$)

16

Match Column-I with Column-II :

Column-I
($$x$$-t graphs)
Column-II
($$v$$-t graphs)
A. JEE Main 2023 (Online) 30th January Morning Shift Physics - Motion in a Straight Line Question 35 English 1 I. JEE Main 2023 (Online) 30th January Morning Shift Physics - Motion in a Straight Line Question 35 English 2
B. JEE Main 2023 (Online) 30th January Morning Shift Physics - Motion in a Straight Line Question 35 English 3 II. JEE Main 2023 (Online) 30th January Morning Shift Physics - Motion in a Straight Line Question 35 English 4
C. JEE Main 2023 (Online) 30th January Morning Shift Physics - Motion in a Straight Line Question 35 English 5 III. JEE Main 2023 (Online) 30th January Morning Shift Physics - Motion in a Straight Line Question 35 English 6
D. JEE Main 2023 (Online) 30th January Morning Shift Physics - Motion in a Straight Line Question 35 English 7 IV. JEE Main 2023 (Online) 30th January Morning Shift Physics - Motion in a Straight Line Question 35 English 8

Choose the correct answer from the options given below:

17

A ball of mass $$200 \mathrm{~g}$$ rests on a vertical post of height $$20 \mathrm{~m}$$. A bullet of mass $$10 \mathrm{~g}$$, travelling in horizontal direction, hits the centre of the ball. After collision both travels independently. The ball hits the ground at a distance $$30 \mathrm{~m}$$ and the bullet at a distance of $$120 \mathrm{~m}$$ from the foot of the post. The value of initial velocity of the bullet will be (if $$g=10 \mathrm{~m} / \mathrm{s}^{2}$$) :

18

A person has been using spectacles of power $$-1.0$$ dioptre for distant vision and a separate reading glass of power $$2.0$$ dioptres. What is the least distance of distinct vision for this person :

19

In a series LR circuit with $$\mathrm{X_L=R}$$, power factor P1. If a capacitor of capacitance C with $$\mathrm{X_C=X_L}$$ is added to the circuit the power factor becomes P2. The ratio of P1 to P2 will be :

20

In the following circuit, the magnitude of current I1, is ___________ A.

JEE Main 2023 (Online) 30th January Morning Shift Physics - Current Electricity Question 98 English

21

In an experiment for estimating the value of focal length of converging mirror, image of an object placed at $$40 \mathrm{~cm}$$ from the pole of the mirror is formed at distance $$120 \mathrm{~cm}$$ from the pole of the mirror. These distances are measured with a modified scale in which there are 20 small divisions in $$1 \mathrm{~cm}$$. The value of error in measurement of focal length of the mirror is $$\frac{1}{\mathrm{~K}} \mathrm{~cm}$$. The value of $$\mathrm{K}$$ is __________.

22

The general displacement of a simple harmonic oscillator is $$x = A\sin \omega t$$. Let T be its time period. The slope of its potential energy (U) - time (t) curve will be maximum when $$t = {T \over \beta }$$. The value of $$\beta$$ is ______________.

23

In Young's double slit experiment, two slits $$S_{1}$$ and $$S_{2}$$ are '$$d$$' distance apart and the separation from slits to screen is $$\mathrm{D}$$ (as shown in figure). Now if two transparent slabs of equal thickness $$0.1 \mathrm{~mm}$$ but refractive index $$1.51$$ and $$1.55$$ are introduced in the path of beam $$(\lambda=4000$$ $$\mathop A\limits^o $$) from $$\mathrm{S}_{1}$$ and $$\mathrm{S}_{2}$$ respectively. The central bright fringe spot will shift by ___________ number of fringes.

JEE Main 2023 (Online) 30th January Morning Shift Physics - Wave Optics Question 45 English

24

A thin uniform rod of length $$2 \mathrm{~m}$$, cross sectional area '$$A$$' and density '$$\mathrm{d}$$' is rotated about an axis passing through the centre and perpendicular to its length with angular velocity $$\omega$$. If value of $$\omega$$ in terms of its rotational kinetic energy $$E$$ is $$\sqrt{\frac{\alpha E}{A d}}$$ then value of $$\alpha$$ is ______________.

25

A horse rider covers half the distance with $$5 \mathrm{~m} / \mathrm{s}$$ speed. The remaining part of the distance was travelled with speed $$10 \mathrm{~m} / \mathrm{s}$$ for half the time and with speed $$15 \mathrm{~m} / \mathrm{s}$$ for other half of the time. The mean speed of the rider averaged over the whole time of motion is $$\frac{x}{7} \mathrm{~m} / \mathrm{s}$$. The value of $$x$$ is ___________.

26

JEE Main 2023 (Online) 30th January Morning Shift Physics - Electromagnetic Induction Question 45 English

As per the given figure, if $$\frac{\mathrm{dI}}{\mathrm{dt}}=-1 \mathrm{~A} / s$$ then the value of $$\mathrm{V}_{\mathrm{AB}}$$ at this instant will be ____________ $$\mathrm{V}$$.

27

In a screw gauge, there are 100 divisions on the circular scale and the main scale moves by $$0.5 \mathrm{~mm}$$ on a complete rotation of the circular scale. The zero of circular scale lies 6 divisions below the line of graduation when two studs are brought in contact with each other. When a wire is placed between the studs, 4 linear scale divisions are clearly visible while $$46^{\text {th }}$$ division the circular scale coincide with the reference line. The diameter of the wire is ______________ $$\times 10^{-2} \mathrm{~mm}$$.

28

A point source of light is placed at the centre of curvature of a hemispherical surface. The source emits a power of $$24 \mathrm{~W}$$. The radius of curvature of hemisphere is $$10 \mathrm{~cm}$$ and the inner surface is completely reflecting. The force on the hemisphere due to the light falling on it is ____________ $$\times~10^{-8} \mathrm{~N}$$.

29

A capacitor of capacitance $$900 \mu \mathrm{F}$$ is charged by a $$100 \mathrm{~V}$$ battery. The capacitor is disconnected from the battery and connected to another uncharged identical capacitor such that one plate of uncharged capacitor connected to positive plate and another plate of uncharged capacitor connected to negative plate of the charged capacitor. The loss of energy in this process is measured as $$x \times 10^{-} { }^{2} \mathrm{~J}$$. The value of $$x$$ is _____________.

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