KEAM Paper 1 Mock Test - 10 - JEE MCQ

# KEAM Paper 1 Mock Test - 10 - JEE MCQ

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## 120 Questions MCQ Test KEAM Mock Test Series 2024 - KEAM Paper 1 Mock Test - 10

KEAM Paper 1 Mock Test - 10 for JEE 2024 is part of KEAM Mock Test Series 2024 preparation. The KEAM Paper 1 Mock Test - 10 questions and answers have been prepared according to the JEE exam syllabus.The KEAM Paper 1 Mock Test - 10 MCQs are made for JEE 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for KEAM Paper 1 Mock Test - 10 below.
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KEAM Paper 1 Mock Test - 10 - Question 1

### A resistance of 40 ohm and an inductance of 95.5 millihenry are connected in series in a 50 cycles/second A.C. circuit. The impedance of this combination is very nearly

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 1
KEAM Paper 1 Mock Test - 10 - Question 2

### A coil of 40 H inductance is connected in series with a resistance of 8 Ω and the combination is joined to the terminals of a 2 V battery. The time-constant of the circuit is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 2

In case of an inductive resistive circuit, the time constant is given as L(eq)/R(eq).

So, in the given case

L(eq)=40H

R(eq)=8 ohm

Thus, time cons.=40/8=5s

KEAM Paper 1 Mock Test - 10 - Question 3

### An object of mass 10 kg is whirled round a horizontal circle of radius 4 m by a revolving string inclined 30º to the vertical. If the uniform speed of the object is 5 ms⁻1, the tension in the string is

KEAM Paper 1 Mock Test - 10 - Question 4

The innermost orbit of the hydrogen atom has a diameter 1.06 Å. The diameter of tenth orbit is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 4
Radius of an atom is directly proportional to n^2 and
radius of nth orbit = Radius of first orbit multiplied by n^2
so that will give you
diameter of n = 10 orbit
will be

1.06x (10)^2= 106 Å
KEAM Paper 1 Mock Test - 10 - Question 5

For the production of X-rays, the target should be made of

KEAM Paper 1 Mock Test - 10 - Question 6

The mass of photon at rest is

KEAM Paper 1 Mock Test - 10 - Question 7

An electric dipole is placed along the X-axis at the origin O. A point P is at a distance of 20 cm from this origin such that OP makes an angle π/3 with the X axis. If electric field at P makes an angle θ with X-axis, the value of θ is

KEAM Paper 1 Mock Test - 10 - Question 8

Two charged conducting spheres of radii a and b are connected to each other by a wire. The ratio of electric fields at the surface of two spheres is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 8
KEAM Paper 1 Mock Test - 10 - Question 9

A lift is moving upward with increasing speed with acceleration 'a'. The apparent weight will be

KEAM Paper 1 Mock Test - 10 - Question 10

If the coefficient of friction between the tyres and the road is 0.4, then maximum speed of a car on a road-turn of radius 30 m, will be

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 10

KEAM Paper 1 Mock Test - 10 - Question 11

Two NOT gates are connected at the two inputs of a NAND gate. This combination will behave like

KEAM Paper 1 Mock Test - 10 - Question 12

A long solenoid has a radius a and number of turns per unit length is n. If it carries a current I, then the magnetic field on its axis is directly propotional to

KEAM Paper 1 Mock Test - 10 - Question 13

A horizontal pipe line carries water in a streamline flow. At a point along the pipe where cross-sectional area is 10 cm2, the velocity of water is 1 m-s⁻1 and pressure is 2000 Pa. The pressure of water, at another point where cross-sectional area is 5 cm2, is (Density of water = 1000 kg-m⁻3)

KEAM Paper 1 Mock Test - 10 - Question 14

A particle has an initial velocity of 3 i ‸ + 4 j ‸ and an acceleration of 0.4 i ‸ + 0.3 j ‸ . Its speed after 10s is-

KEAM Paper 1 Mock Test - 10 - Question 15

If in a nuclear reactor using U235 as fuel, the power output is 4.8 mega watts, the number of fissions per second is:
(energy released per fission of U235 = 200 MeV; 1eV = 1.6 x 10 − 19 J)

KEAM Paper 1 Mock Test - 10 - Question 16

In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Air quickly leaking out of a balloon becomes cooler.
Reason(R): The leaking air undergoes adiabatic expansion. Reason(R): The leaking air undergoes adiabatic expansion.

KEAM Paper 1 Mock Test - 10 - Question 17

In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A):If the string of a descending lift is broken, then it will fall down like a free body.
Reason(R):The acceleration of a free body is always 'g'.

KEAM Paper 1 Mock Test - 10 - Question 18

A circular disc is rotating with angular velocity ω. A man sitting at the edge walks towards the centre of disc, then the angular velocity ω

KEAM Paper 1 Mock Test - 10 - Question 19

During an adiabatic process, the pressure of a gas is proportional to the cube of its adiabatic temperature. The value of for that gas is

KEAM Paper 1 Mock Test - 10 - Question 20

SI unit of magnetic dipole moment is

KEAM Paper 1 Mock Test - 10 - Question 21

The maximum number of possible interference maxima for slit-separation equal to twice the wavelength in Young's double-slit experiment, is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 21

KEAM Paper 1 Mock Test - 10 - Question 22

Two identical light waves, propagating in the same direction, have a phase difference δ . After they superpose the intensity of the resulting wave will be proportional to

KEAM Paper 1 Mock Test - 10 - Question 23

When exposed to sunlight, thin films of oil on water often exhibit brilliant colours due to the phenomenon of

KEAM Paper 1 Mock Test - 10 - Question 24

The intensity of a harmonic wave

KEAM Paper 1 Mock Test - 10 - Question 25

The transition from the state n = 4 to n = 3 in hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from-

KEAM Paper 1 Mock Test - 10 - Question 26

A capacitor of capacity C₁ is charged by connecting it across a battery of e.m.f. V₀. The battery is then removed and the capacitor is connected in parallel with an uncharged capacitor of capacity C₂. The potential difference across this combination is

KEAM Paper 1 Mock Test - 10 - Question 27

If a particle of mass m is projected from the lowest point of smooth vertical circle of radius 'A' with velocity 5 a g the pressure at its lowest point will be—

KEAM Paper 1 Mock Test - 10 - Question 28

A series combination of two resistors 1 Ω each is connected to a 12 V battery of internal resistance 0.4Ω. The current flowing through it is

KEAM Paper 1 Mock Test - 10 - Question 29

The figure to the right shows an edge-on view of three extremely large, parallel insulating sheets positively charged with uniform and identical surface charge densities. In which of the regions shown is the electric field a maximum?

KEAM Paper 1 Mock Test - 10 - Question 30

A straight wire of diameter 0.5 mm carrying a current of 1 A is replaced by another wire of 1 mm diameter carrying the same current. The strength of magnetic field far away is

KEAM Paper 1 Mock Test - 10 - Question 31

In a LCR circuit capacitance is changed from C to 2C. For the resonant frequency to remain unchanged, the inductance should be changed from L to

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 31

KEAM Paper 1 Mock Test - 10 - Question 32

A transformer is employed to reduce 220 V to 11 V. The primary draws a current of 5 A and the secondary 90 A. The efficiency of the transformer is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 32

Primaray  power = 220 *5 = 1100 w
Secondary power = 11*90 = 990 w
So , efficiency = 990w/1100w = 90 %

KEAM Paper 1 Mock Test - 10 - Question 33

Moderator used in nuclear reactor is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 33

Heavy water is used in certain types of nuclear reactors, where it acts as a neutron moderator  to slow down neutrons so that they are more likely to react with the fissile uranium-235 than with uranium-238, which captures neutrons without fissioning.

KEAM Paper 1 Mock Test - 10 - Question 34

The unit of intensity of electric field is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 34

The SI unit of electric field strength is newtons per coulomb (N/C) or volts per meter (V/m). The force experienced by a very small test charge q placed in a field E in a vacuum is given by E = F/q, where F is the force experienced.

KEAM Paper 1 Mock Test - 10 - Question 35

In a hydrogen atom, when an electron jumps from second orbit to first orbit, the wavelength of spectral line emitted by hydrogen atom is

KEAM Paper 1 Mock Test - 10 - Question 36

“If a particle of mass m is projected from the lowest point of smooth vertical circle of radius 'A' with velocity √(5ag) the force at its lowest point will be”

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 36

At lowest point centrifugal force is equal to mv2/a in downward direction

=> total downward force = mg + mv2/a
= mg + m 5ag/a
= mg + 5 mg
= 6mg

KEAM Paper 1 Mock Test - 10 - Question 37

A particle of mass m and charge q is placed at rest in a uniform electric field E and then released. The kinetic energy attained by the particle after moving a distance y is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 37

By conservation of energy, the increase in kinetic energy will be the decrease in potential energy.

Thus, the kinetic energy obtained is simply: qEy

KEAM Paper 1 Mock Test - 10 - Question 38

An electron having charge e and mass m is moving in a uniform electric field E. Its acceleration will be

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KEAM Paper 1 Mock Test - 10 - Question 39

25 N force is required to raise 75 kg mass from a pulley. If rope is pulled 12 m, then the load is lifted to 3 m, the efficiency of pulley system will be

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 39

Efficiency = output/input = (75x3) / (25x12)
=75/100 =75%

KEAM Paper 1 Mock Test - 10 - Question 40

Two wires of same length are shaped into a square and a circle. If they carry same current, ratio of the magnetic moments is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 40

Let magnetic moment of square wire be μ1  = I1A1
Let magnetic moment of circle wire be μ2= I2A2
If the wires carry same current then the ratio of their magnetic moments will be

KEAM Paper 1 Mock Test - 10 - Question 41

In a capillary tube, water rises by 1.2 mm. The height of water that will rise in another capillary tube having half the radius of the first, is

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KEAM Paper 1 Mock Test - 10 - Question 42

Three forces start acting simultaneously on a particle moving with velocity v → . These forces are represented in magnitude and direction by the three sides of a triangle ABC (as shown). The particle will now move with velocity

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 42

According to triangle law of vector addition, if three vectors are represented by three sides of a triangle taken in same order, then their resultant will be zero. Here, three forces acting on the particle are represented by the three sides of a triangle taken in one order, thus the resultant is zero. So, in presence of zero external force, the particle's velocity remains unchanged.

KEAM Paper 1 Mock Test - 10 - Question 43

Four bodies P, Q, R and S are projected with equal velocities having angles of projection 15º, 30º, 45º and 60º with the horizontal respectively. The body having shortest range is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 43

When the angle of projection is very far from 45° then range will be minimum.

KEAM Paper 1 Mock Test - 10 - Question 44

An electric current of 5 A is same as

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 44

Hence 5A of current is same as 5 C/sec

KEAM Paper 1 Mock Test - 10 - Question 45

The nucleus of 56Ba141 contains ---- neutrons

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 45

Given ,

=> atomic mass=141

=>atomic number=56

So, neutrons=atomic mass-atomic number

=141-56

=85

KEAM Paper 1 Mock Test - 10 - Question 46

Assertion : The work done during a round trip is always zero.
Reason : No force is required to move a body in its round trip.

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 46

In a round trip work done is zero only when the force is conservative in nature.  Force is always required to move a body in a conservative or non-conservative field

KEAM Paper 1 Mock Test - 10 - Question 47

In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Study of Fraunhofer lines in the spectrum of sun led to the discovery of hydrogen.
Reason(R):Fraunhofer lines are dark lines in the continuous solar spectrum.

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 47

In 1868 Lockyer observed a line among the Fraunhofer lines which could not be traced in the spectrum of any element on earth. So it was assumed that there was some new element in the sun's chromsphere. It was named helium. In 1895 Ramsay found this gas on earth. Thus, the study of Fraunhofer lines led to the discovery of new elements.

KEAM Paper 1 Mock Test - 10 - Question 48

A body A of mass M while falling vertically downwards under gravity breaks into two parts, a part B of mass M/3 and body C of mass 2M/3. The centre of mass of the bodies B and C taken together

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 48

No horizontal external force is acting
∴ acm = 0
since vcm = 0
∴ Δxcm = 0

KEAM Paper 1 Mock Test - 10 - Question 49

A Carnot engine used first an ideal monoatomic gas and then an ideal diatomic gas. If the source and sink temperature are 411ºC and 69ºC respectively and the engine extracts 1000 J of heat in each cycle, then area enclosed by the P-V diagram is

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KEAM Paper 1 Mock Test - 10 - Question 50

The Martians use force (F), acceleration (A) and time (T) as their fundamental physical quantities. The dimensions of length on Martians system are

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 50

Acceleration

KEAM Paper 1 Mock Test - 10 - Question 51

Wave optics is based on wave theory of light put forward by Huygen and modified later by

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 51

The Huygens–Fresnel principle (named after Dutch physicist Christiaan Huygens and French physicist Augustin-Jean Fresnel) is a method of analysis applied to problems of wave propagation both in the far-field limit and in near-field diffraction.

It states that every point on a wavefront is itself the source of spherical wavelets. The sum of these spherical wavelets forms the wavefront.

KEAM Paper 1 Mock Test - 10 - Question 52

Doppler's effects in sound and light are

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 52

An apparent change in the frequency of waves, as of sound or light, occurring when the source and observer are in motion relative to each other, with the frequency increasing when the source and observer approach each other anddecreasing when they move apart.

KEAM Paper 1 Mock Test - 10 - Question 53

The ray of light

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 53

A perpendicular drawn to the surface of a wavefront at any point in the direction of propagation of light is called as wave normal. The direction of propagation of a wave front is given by a ray of light. Therefore, a wave normal represents a ray of light.

KEAM Paper 1 Mock Test - 10 - Question 54

The phase difference between two points separated by 0.8 m in a wave of frequency 120 Hz is 90º. Then the velocity of wave will be

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 54

Here, path difference Δx=0.8m Frequency n =120 Hz Phase difference is ϕ=0.5π The phase difference is given by

Hence, the wave velocity is given by v = nλ (where λ is the wavelength of wave) =120 × 2.3 = 384m/s

KEAM Paper 1 Mock Test - 10 - Question 55

Which of the following is not a statement?

KEAM Paper 1 Mock Test - 10 - Question 56

When the electron in a hydrogen atom of mass M undergoes transition from an orbit of higher quantum number n2 to an orbit of lower quantum number n1, the recoil velocity acquired by the atom is (Rydberg's constant = R, Planck's constant = h)

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 56

The wave number of the photon emitted because of the electron transition is

ν' = 1/λ = R(1/(n1)2 – 1/(n2)2) where λ is the wave length of the photon and R is Rydberg’s constant.

The momentum of the photon is p = h/λ = hR(1/(n1)2 – 1/(n2)2) where h is Planck’s constant.

When the photon is emitted with this momentum, the atom recoils (like a gun firing a bullet) with an equal and opposite momentum. Therefore, the recoil velocity of the atom is given by

v = p/M = (hR/M)(1/(n1)2 – 1/(n2)2).

KEAM Paper 1 Mock Test - 10 - Question 57

A 5.0 μ F capacitor is charged to a potential difference of 800 V and discharged through a conductor. The energy given to the conductor during the discharge is

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KEAM Paper 1 Mock Test - 10 - Question 58

A stone of mass 1 kg tied to a light inextensible string of length L = 10/3 m is whirling in a circular path of radius L in a vertical plane. If the ratio of the maximum tension in the string to the minimum tension in the string is 4 and if g is taken to be 10 m/sec2, the speed of the stone at the highest point of the circle is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 58

The ratio of maximum (T2) to the minimum tension is

Now, the difference between the two tensions should be 6 mg.

Hence, we have

Now, the tension at the top of the circle is

KEAM Paper 1 Mock Test - 10 - Question 59

If six identical cells each having an e.m.f of 6V are connected in parallel, the E.M.F of the combination is

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 59

In parallel combination  Eeq=E=6V

KEAM Paper 1 Mock Test - 10 - Question 60

There are 20 divisions in 4 cm of the main scale. The vernier scale has 10 divisions. The least count of the instrument is

KEAM Paper 1 Mock Test - 10 - Question 61

A mixture of Al and Zn weighing 1.67 g was completely dissolved in acid, and the evolved 1.69 litres of hydrogen gas was measured at 273 K and one atmosphere pressure. The respective masses of Al and Zn in the original mixture were

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 61
Let 'a' g and 'b 'g be the weights of Al and Zn in the mixture.

a + b = 1.67 … (1)

Meq of Al + Meq of Zn = Meq of H2

From equations (1) and (2)

a = 1.25 g Al

b = 0.42 g Zn

KEAM Paper 1 Mock Test - 10 - Question 62

In which of the following sets of quantum numbers will an electron have the highest energy?

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 62
The orbital with highest value of (n + l) has the highest energy.

For set, 3, 2, 2, 1/2.

Value of n + l is 3 + 2 = 5

It is the highest among given options, hence electron will have the highest energy for this set of quantum numbers.

KEAM Paper 1 Mock Test - 10 - Question 63

In aqueous solution, the ionisation constants for carbonic acid are K1 = 4.2 × 10-7 and K2 = 4.8 × 10-11.

Select the correct statement for a saturated 0.034 M solution of carbonic acid.

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 63

Second dissociation constant is much smaller than the first one. Just a small fraction of total HCO-3 formed will undergo second stage of ionisation. Hence, in saturated solution,

KEAM Paper 1 Mock Test - 10 - Question 64

In which of the following arrangements is the order not according to the property indicated against it?

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 64
As we move from left to right across a period, ionisation enthalpy increases with increasing atomic number. So, the order of increasing ionisation enthalpy should be B < C < N < O.

But, N (1s2 2s2 2p3) has a stable half filled electron configuration. So, ionisation enthalpy of nitrogen is greater than oxygen. So, the correct order of increasing first ionisation enthalpy is B < C < O < N.

Hence, the order indicated in the option (2) is correct.

KEAM Paper 1 Mock Test - 10 - Question 65

The metallic lustre exhibited by sodium is explained by

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 65
The metallic lustre of sodium is due to oscillations of loose electrons. Metals are lustrous because of the free electrons they have. The free electrons can move freely in the metal, causing any light incident on them to get reflected back.
KEAM Paper 1 Mock Test - 10 - Question 66

What would happen when a solution of potassium chromate is treated with an excess of dilute nitric acid?

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 66
Dilute nitric acid converts chromate into dichromate and H2O.

2K2CrO4 + 2HNO3 → K2Cr2O7 + 2KNO3 + H2O

⇒ 2CrO4−2 ⇌ H+ + Cr2O72− + H2O

Acidic medium shifts the equilibrium in the direction of the dichromate ion.

KEAM Paper 1 Mock Test - 10 - Question 67

Which of the following is not aromatic?

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 67

Cyclopentadienyl cation is not aromatic as it contains only 4 pi electrons. So, it does not follow (4n + 2) pi electron rule.

KEAM Paper 1 Mock Test - 10 - Question 68

Which of the following statements is correct?

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 68
(1) Hydrogenation of an alkene is a heterogeneous process which occurs on the surface of a solid catalyst (PtO2 or Pd/C). The addition occurs with syn stereochemistry (both hydrogens add from the same side). For cis isomer, the product is a meso compound.

(2) The product is a racemic mixture.

(3) The addition of two hydroxyl groups involves syn addition (on the same side of a double bond). The result is same as that of hydrogenation. The cis isomer produces meso compound.

(4) The addition of two hydroxyl groups involves syn addition (on the same side of a double bond). The result is same as that of hydrogenation. The trans isomer produces racemic mixture.

KEAM Paper 1 Mock Test - 10 - Question 69

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KEAM Paper 1 Mock Test - 10 - Question 70

Which of the following has the composition of Schweizer reagent?

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 70
Schweizer reagent is the chemical complex tetraamminediaquacopper dihydroxide, [Cu(NH3)4(H2O)2](OH)2. It is prepared by precipitating copper (II) hydroxide from an aqueous solution of copper sulphate using sodium hydroxide or ammonia, then dissolving the precipitate in a solution of ammonia.
KEAM Paper 1 Mock Test - 10 - Question 71

Which of the following pair is expected to exhibit the same colour in solution?

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 71

In CuCl2, Cu2+ has d9 configuration, exhibit d − d transition and show colour. Similarly in VOCl2, V4+ has d1 configuration, can exhibit d − d transition and show colour.

MnCl2 = Pink colour

Zn2+ ⇒ 3d10 (Colourless)

Hg2+ ⇒ 5d10(Colourless)

V = 4s23d3

V4+ = 4s03d1 ((d − d transition)

Cu+2 = d9 configuration = one unpaired e.

Since, in both CuCl2 and VOCl2,Cu2+ and V4+ ion contain 1 unpaired electron each, so their colour may be same.

KEAM Paper 1 Mock Test - 10 - Question 72

The hybridisation of orbitals of N atoms in NO3, NO+2 and NH+4 are respectively-

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 72
The hybridisation of the central atom can be decided based on the number of atomic orbitals used in the hybridisation. This can be found using the formula

Where,

H = Number of hybrid orbitals;

V.E.= Number of valence electrons on the central atom;

M = Number of monovalent atoms attached to the central atom;

C = Magnitude of charge if the given species is a cation;

A = Magnitude of charge if the given species is an anion.

Based on this, the hybridisation of NO3, NO2+ and NH4+ can be found out as:

KEAM Paper 1 Mock Test - 10 - Question 73

The sp3d2 hybridisation of central atom of a molecule would lead to

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 73
sp3d2 hybridised molecule have octahedral geometry(square bipyramidal)
KEAM Paper 1 Mock Test - 10 - Question 74

The first ionisation energies in eV/atome of magnesium and aluminium are respectively given by which of the following?

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 74

IE of Mg>IE of Al

Mg: 1s2, 2s22p6, 3s2

Al: 1s2, 2s22p6, 3s23p1

The first electron remove from Mg is more difficult because it has fulfilled orbital configuration while Al has partial filled orbital configuration.

KEAM Paper 1 Mock Test - 10 - Question 75

A graph plotted between log k versus 1/T for calculating activation energy is shown by:

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 75
A graph plotted between log k versus 1/T for calculating activation energy is shown as

From the Arrhenius equation

Comparing with the equation of straight line, y = mx + c, we get a straight line having positive intercept on y-axis and negative slope.

KEAM Paper 1 Mock Test - 10 - Question 76

Toluene reacts, with excess of Cl2 in presence of sunlight to give a product, which on hydrolysis followed by reaction with NaOH gives

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 76
Toluene reacts with excess of Cl2 in presence of sunlight, the last product of this reaction is benzotrichloride which on hydrolysis gives benzoic acid, and it gives sodium benzoate on reaction with NaOH.

KEAM Paper 1 Mock Test - 10 - Question 77

Which of the aldehyde is most reactive?

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 77
Among the carbonyl compounds, the reactivity decreases with an increase in the number of alkyl groups and the size of the alkyl group because the positive charge on the carbon atom decreases due to +I effect of alkyl groups.

Thus, the correct order reactivity is HCHO > CH3CHO > C6H5CHO.

KEAM Paper 1 Mock Test - 10 - Question 78

The degree of dissociation (α) of a weak electrolyte AxBy is related to Van't Hoff factor (i)i by the expression

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 78

Total = 1 + α(x + y − 1) or i = 1 + α(x + y − 1)

KEAM Paper 1 Mock Test - 10 - Question 79

Which one of the following is the structure of polyacrylonitrile?

Detailed Solution for KEAM Paper 1 Mock Test - 10 - Question 79

Polyacrylonitrile (PAN), a synthetic resin prepared by the polymerization of acrylonitrile.

Polyacrylonitrile (PAN), also known as polyvinyl cyanide and Creslan 61, is a synthetic, semicrystalline organic polymer resin, with the linear formula (C3H3N)n.

KEAM Paper 1 Mock Test - 10 - Question 80