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NEET Practice Test - 21 - NEET MCQ


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180 Questions MCQ Test NEET Mock Test Series 2025 - NEET Practice Test - 21

NEET Practice Test - 21 for NEET 2024 is part of NEET Mock Test Series 2025 preparation. The NEET Practice Test - 21 questions and answers have been prepared according to the NEET exam syllabus.The NEET Practice Test - 21 MCQs are made for NEET 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for NEET Practice Test - 21 below.
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NEET Practice Test - 21 - Question 1

Among the following pairs of ions, the lower oxidation state in aqueous solution is more stable than the other, in

Detailed Solution for NEET Practice Test - 21 - Question 1
As we move down in groups 13,14 and 15, inertness of ns2 electrons of valence shell increases (inert pair effect). Thus in metals present at the bottom of the groups 13,14, and 15 lower oxidation state becomes more important, viz. Pb (+2 state rather +4), Bi (+3 state rather +5) and Ti (+1 rather than+3).
NEET Practice Test - 21 - Question 2

The optically inactive compound from the following is:

Detailed Solution for NEET Practice Test - 21 - Question 2
The optically inactive compound must contain achiral carbon atom(s). Option (d) contains achiral carbon atom

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NEET Practice Test - 21 - Question 3

The correct order of increasing [H3O+] in the following aqueous solutions is

Detailed Solution for NEET Practice Test - 21 - Question 3
H2SO4 is a strong acid hence pH < 7 , or [H]+ >10-7, the aqueous solution of NaCl is neutral hence pH a 7 or [H+] ≈ 10-7. The aqueous solution of NaNO2 will be basic hence pH > 7 or [H+] < 10-7 H2S is a weak acid. Therefore, the correct order will be 0.01 M NaNO2 < 0.01 M NaCl < 0.01 M H2S < 0.01M H2S04
NEET Practice Test - 21 - Question 4

All form ideal solution except

Detailed Solution for NEET Practice Test - 21 - Question 4
C2H5I and C2H5OH form non-ideal solutions.
NEET Practice Test - 21 - Question 5

The hybridization of atomic orbitals of nitrogen in NO2+ , NO2- and NH4+ are

Detailed Solution for NEET Practice Test - 21 - Question 5
NO2+ = 1/2 [5 + 0 + 0 - 1] = 2 sp;

NO2- = 1/2 [5 + 0 + 1 - 0] = 3 sp2;

NO4+ = 1/2 [5 + 4 + 0 - 1] = 4 sp3;

NEET Practice Test - 21 - Question 6

Which of the following has correct for increasing basic strength?

Options

(a) MgO < BeO < CaO < BaO

(b) BeO < MgO < CaO < BaO

(c) BaO < CaO < MgO < BeO

(d) CaO < BaO < BeO < MgO


Detailed Solution for NEET Practice Test - 21 - Question 6
BeO < MgO < CaO < BaO

The basic character of the oxides increases down the group.

Among these BeO is amphoteric.

NEET Practice Test - 21 - Question 7

Which of the following is commercially known as oxone?

Detailed Solution for NEET Practice Test - 21 - Question 7
(Na2O2 + HCl) is commercially known as ozone and is used for bleaching of delicate fibres.
NEET Practice Test - 21 - Question 8

The unusual properties of water in the condensed phase (liquid and solid states) are due to the

Detailed Solution for NEET Practice Test - 21 - Question 8
The unusual properties of water in the condensed phase (liquid and solid states) are due to the presence of
NEET Practice Test - 21 - Question 9

Which one of the following statements concerning lanthanide elements is false?

Detailed Solution for NEET Practice Test - 21 - Question 9
The ionic radii of trivalent lanthanides decreases progressively with increase in atomic number. This decrease is known as lanthanide contraction.
NEET Practice Test - 21 - Question 10

The hypothetical complex chlorodiaquotriammine cobalt (III) chloride can be represented as

Detailed Solution for NEET Practice Test - 21 - Question 10
Chloro diaquatriammine cobalt (III) chloride is [CoCl (NH3)3 (H2O)2 ] Cl2
NEET Practice Test - 21 - Question 11

For the compoundsCH3Cl, CH3Br, CH3I and CH3F, the correct order of increasing C-halogen bond length is:

Detailed Solution for NEET Practice Test - 21 - Question 11
The correct order of increasing bond length is CH3F< CH3Cl < CH3Br < CH3I
NEET Practice Test - 21 - Question 12

The ammonia (NH3) released on quantitative reaction of 0.6 g urea (NH2CONH2) with sodium hydroxide (NaOH) can be neutralized by:

Detailed Solution for NEET Practice Test - 21 - Question 12
1 mol of urea = 2 mol of NH3

60 g of urea = 2 mol of NH3

0.6 g of urea = 2/60 x 0.6mol = 0.02 mol of NH3

mol of NH3 = mol of HCl

∴ mol of HCl = 0.02 mol

⇒ Normality of HC1 = 0.2 N

Volume of HCL = 100 mL

NEET Practice Test - 21 - Question 13

The INCORRECT statement is :

Detailed Solution for NEET Practice Test - 21 - Question 13

(a) Bronze contains 88-96% Cu and 4-12% Sn.

(b) Cast iron is used to make wrought iron.

(c) German silver contains 50% Cu, 30% Zn & 20% Ni.

(d) Brass contains 70% Cu and 30% Zn

NEET Practice Test - 21 - Question 14

Acetylenic hydrogens are acidic because

Detailed Solution for NEET Practice Test - 21 - Question 14
The acidity of acetylene or 1 -alkynes can be explained on the basis of molecular orbital concept according to which formation of C — R bond in acetylene involves ip- hybridised carbon atom. Now since s electrons are closer to the nucleus than p electrons, the electrons present in a bond having more s character will be correspondingly more closer to the nucleus.

Thus owing to high s character of the C — FT bond in alkynes (s = 50%), the electrons constituting this bond are more strongly held by the carbon nucleus (i.e. The acetylenic carbon atom or the sp orbital acts as more electronegative species than the sp2- and sp1 with the result the hydrogen present on such a carbon atom (=C — H) can be easily removed as a proton.

NEET Practice Test - 21 - Question 15

Aqueous solution of group 2 is precipitated by adding Na2CO3, then this precipitate is tested on flame, no light in visible region is observed , this element can be

Detailed Solution for NEET Practice Test - 21 - Question 15
Electrons in Mg due to its small size are tightly bound so they cannot be excited by the flame.
NEET Practice Test - 21 - Question 16

A reaction at 1 bar is non–spontaneous at low temperature but becomes spontaneous at high temperature. Identify the correct statement about the reaction among the following:

Detailed Solution for NEET Practice Test - 21 - Question 16
∆G = ∆H-T∆S

For a spontaneous reaction ∆G = -ve

which is possible when both ∆H and ∆S are positive at high temperature and hence the reaction becomes spontaneous.

NEET Practice Test - 21 - Question 17

When CH3Cl and AlCl3 are used in Friedel-Crafts reaction, the electrophile is

Detailed Solution for NEET Practice Test - 21 - Question 17

NEET Practice Test - 21 - Question 18

The monomer of the polymer;

Detailed Solution for NEET Practice Test - 21 - Question 18
Addition of monomers follows isoprene rule

NEET Practice Test - 21 - Question 19

The correct statement for the molecule, CsI3 is:

Detailed Solution for NEET Practice Test - 21 - Question 19
Csl3, dissociates as Csl3 → Cs+ + I3-
NEET Practice Test - 21 - Question 20

Which of the following statements about the advantage of roasting of sulphide ore before reduction is not true?

Detailed Solution for NEET Practice Test - 21 - Question 20
The sulphide ore is roasted to oxide before reduction because the ΔGf° of most of the sulphides are greater than those of CS2 and H2S, therefore neither C nor H can reduce metal sulphide to metal. Further, the standard free energies o f formation o f oxide are much less than those o f SO2. Hence oxidation of metal sulphides to metal oxide is thermodynamically favourable.
NEET Practice Test - 21 - Question 21

Pollution in large cities can be checked only by:

NEET Practice Test - 21 - Question 22

Which of the following metal ions will form complexes with the same magnetic moment and geometry irrespective of the nature of ligands?

Detailed Solution for NEET Practice Test - 21 - Question 22
Cu2+ forms complexes with the same magnetic moment and geometry irrespective of the nature of ligand. It can be explained by electronic configuration.

It has 9 electrons in a 3d shell. Hence any incoming ligand whether it is strong or weak will result in the formation of the same geometry (if the number of ligands is same) because any ligand can do nothing with this unpaired e- in 3d shell. Moreover, the complex formed will have the same magnetic moment due to this unpaired e-.

NEET Practice Test - 21 - Question 23

Enthalpy and entropy change for a chemical reaction are –2.5 × 103 cals and 7.4 cals deg–1 respectively. At 25°C the reaction is:

Detailed Solution for NEET Practice Test - 21 - Question 23
ΔH = -2.5x 103cal

ΔS = 7.4 cal

ΔG = ΔH - TΔS

= -2 .5 x 103 - 298x7.4 = - 4705 .2 Cal.

ΔG = - ive; so process is spontaneous

ΔG = 0, Equilibrium

ΔG = + ive; Non-spontaneous

NEET Practice Test - 21 - Question 24

One litre of 1 M CuSO4 solution is electrolysed.

After passing 2 F of electricity, molarity of CuSO4 solution will be

Detailed Solution for NEET Practice Test - 21 - Question 24
1 L of 1M CuSO4 = 1 mol of Cu2+

Cu2+ + 2e- → Cu

2 F of electricity will convert dil Cu2+ into Cu, hence [CuSO4] = 0

Thus, (d)

NEET Practice Test - 21 - Question 25

Which is not correct regarding the adsorption of a gas on the surface of a solid?

Detailed Solution for NEET Practice Test - 21 - Question 25
On increasing temperature adsorption of a gas on the surface of solid decreases. Solid adsorb greater amounts of substances at lower temperature.
NEET Practice Test - 21 - Question 26

Match the organic compounds in column-I with the Lassaigne’s test results in column-II appropriately:

Detailed Solution for NEET Practice Test - 21 - Question 26
In Lassaigne's test, fusion with sodium takes place and following species formed respectively.

(a) Aniline → CN-

(b) Benzene sulfonic acid →

(c) Thiourea → S2-

Reaction of CN- with hot and acidic solution of FeSO4 leads to formation of Fe4[Fe(CN)6]3 which is blue in colour. It contains iron in both II and III oxidation states.

Reaction of S2- with sodium nitroprusside

Na2S + Na,[Fe(CN)5NO] → Na4[Fe(CN)5NOS] (violet in colour)

Phenoxide ions reacting with FeCl3 give red colour with FeCl3.

NEET Practice Test - 21 - Question 27

The fraction of total volume occupied by the atoms present in a simple cube is

Detailed Solution for NEET Practice Test - 21 - Question 27
Number of atoms per unit cell = 1

Atoms touch each other along edges. Hence r = a/2 ( r = radius o f atom and a = edge length)

Therefore % fraction

=

= ?/6

= 0.52

NEET Practice Test - 21 - Question 28

Which of the following may be considered to be an organometallic compound?

Detailed Solution for NEET Practice Test - 21 - Question 28
organometallic compounds are those compounds in which there is a bond which involves metal. In chlorophyll there is bond involving metal Mg
NEET Practice Test - 21 - Question 29

In the following reaction ‘A ’ is

Detailed Solution for NEET Practice Test - 21 - Question 29

NEET Practice Test - 21 - Question 30

Which of the following statements is incorrect regarding benzyl chloride?

Detailed Solution for NEET Practice Test - 21 - Question 30
Benzyl chloride (C6H5CH2Cl) is more reactive than vinyl chloride (CH2 = CHCl)
NEET Practice Test - 21 - Question 31

One mole of an ideal gas is allowed to expand reversibly and adiabatically from a temperature of 27°C. If the work done during the process is 3 kJ, then final temperature of the gas is (Cv = 20 J/K)

Detailed Solution for NEET Practice Test - 21 - Question 31
Since the gas expands adiabatically (i.e., no change in enthalpy) so the heat is totally converted into work. For the gas, Cv = 20 J/K. Thus, 20 J of heat is required for 1° change in temperature of the gas.

Heat change involved during the process i.e., work done = 3kJ = 3000J.

Change in temperature = 3000/20 K = 150 K

Initial temperature = 300 K

Since, the gas expands so the temperature decreases and thus final temperature is

300 - 150 = 150K

NEET Practice Test - 21 - Question 32

Carbon and CO gas are used to reduce which of the following pairs of metal oxides for extraction of metals?

NEET Practice Test - 21 - Question 33

Identify the correct order of electron affinity for O, O, F and Na+.

Detailed Solution for NEET Practice Test - 21 - Question 33

NEET Practice Test - 21 - Question 34

Which of the following can not be isoelectronic?

NEET Practice Test - 21 - Question 35

The alkaline earth metals Ba, Sr, Ca and Mg may be arranged in the order of their decreasing first ionisation potential as

Detailed Solution for NEET Practice Test - 21 - Question 35
Mg, Ca, Sr, Ba. As the size increases, the ionisation potential decreases.
NEET Practice Test - 21 - Question 36

Dissolving 120 g of a compound of (mol. wt. 60) in 1000 g of water gave a solution of density 1.12 g/mL. The molarity of the solution is:

Detailed Solution for NEET Practice Test - 21 - Question 36
Given

mass of solute (w) = 120 g

mass of solvent (w) = 1000 g Mol.

mass of solute = 60 g

density of solution = 1.12 g/ mL

From the given data,

Mass of solution = 1000+ 120 = 1120 g

∴ d = Mol. mass / v or v = Mol. mass / d

Volume Solution

V = 1120/1.12 = = 1000 mL or = 1 litre

Now molarity (M ) = W / Mol. mass x V (lit.)

= 120/60 x 1

= 2M

NEET Practice Test - 21 - Question 37

Standard entropy of X2, Y2 and X Y3 are 60, 40 and 50 J K–1 mol–1, respectively. For the reaction, ΔH = -30 kJ. to be at equilibrium, the temperature will be

Detailed Solution for NEET Practice Test - 21 - Question 37
For a reaction to be at equilibrium ΔG = 0. Since

ΔG = ΔH - TΔS so at equilibrium

ΔH - TΔS = 0

or ΔH = TΔS

For the reaction

ΔH = -30 kJ(given)

Calculating ΔS for the above reaction, we get

= 50 - ( 30 + 60) JK-1 = - 40 JK-1

At equilibrium,

TΔS = ΔH

∴ T x (-40) = - 30 x 1000 [lkJ = 1000J]

or

NEET Practice Test - 21 - Question 38

The end product (C) in the following sequence of reactions is

Detailed Solution for NEET Practice Test - 21 - Question 38

NEET Practice Test - 21 - Question 39

A solution is prepared by mixing 8.5 g of CH2Cl2 and 11.95 g of CHCl3. If vapour pressure of CH2Cl2 and CHCl3 at 298 K are 415 and 200 mmHg respectively, the mole fraction of CHCl3 in vapour form is:

(Molar mass of Cl = 35.5 g mol–1)

Detailed Solution for NEET Practice Test - 21 - Question 39
Molar mass of CHCl3 = 119.5 g/mole.

Molar mass of CH2Cl2 = 85 g/mole.

Moles of CHCl3 = 11.95/119.5 = 0.1 mole

Moles of CH2Cl2 = 8.5/85 = 0.1 mole

Mole fraction of CHCl3 = 0.1/0.2 = 0.5 mole.

Mole fraction of CH2Cl2= 0.1/0.2 = 0.5 mole.

(Given-

Vapour pressure of CHCl3 = 200 mm

Hg=0.263 atm.

Vapour pressure of CH2Cl2= 415 mm

Hg = 0.546 atm.) (1 atm=760 mm Hg)

P(above solution) = Mole fraction of CHCl3 x (Vapour pressure of CHCl3) + Mole fraction of CH2CI2, x (Vapour pressure ofCH2Cl2)

= 0.5 x 0.263 + 0.5 x 0.546 = 0.4045

Mole fraction cf CHCl3 in vapour form

= 0.1315/0.4045 = 0325

NEET Practice Test - 21 - Question 40

The decreasing order of reactivity of the following compounds towards nucleophilic substitution (S2N) is

Detailed Solution for NEET Practice Test - 21 - Question 40
SN2 reactions depend upon -I and -M effect on substrates. On increasing the -I and -M effect, the rate of SN2 reaction will increase.
NEET Practice Test - 21 - Question 41

In a reaction A + B C + D, the initial concentrations of A and B were 0.9 mol dm–3 each. At equilibrium the concentration of D was found to be 0.6 mol dm–3. What is the value of equilibrium constant for the reaction

Detailed Solution for NEET Practice Test - 21 - Question 41

A + B C + D

= 4

NEET Practice Test - 21 - Question 42

The compound A on heating gives a colourless gas and a residue which dissolves in water to give B. When excess of CO2 is passed into B and gently heated, A is formed. The compound A is

Detailed Solution for NEET Practice Test - 21 - Question 42

NEET Practice Test - 21 - Question 43

For a reaction of type A + B → products , it is observed that doubling concentration of A causes the reaction rate to be four times as great, but doubling the amount of B does not affect the rate. The rate equation is

Detailed Solution for NEET Practice Test - 21 - Question 43
Let the rate law equation be

r = k [A] x[B]y ............. (i)

when A=2A,

4r=k[2A ]x [B]y .............. (ii)

Divide (2) by (1)

⇒ 4 = (2)x, Hence x = 2

When B = 2B,

r = k [A ] x [2R]> ............... (iii)

∴ Rate =k[A]2[B]0

NEET Practice Test - 21 - Question 44

Complex A has a composition of H12O6Cl3Cr. If the complex on treatment with conc. H2SO4 loses 13.5% of its original mass, the correct molecular formula of A is : [Given : atomic mass of Cr = 52 amu and Cl = 35 amu]

Detailed Solution for NEET Practice Test - 21 - Question 44
Cone. H2SO4 acts as dehydrating agent.

Molar mass of given complex = 266.5 g/mol.

On treating it with a cone. H2S 0 4 the mass lost by the complex = 13.5/100(266.5) ≈ 36g = 2 mole of H2O

NEET Practice Test - 21 - Question 45

The cell constant of a given cell is 0.47 cm–1. The resistance of a solution placed in this cell is measured to be 31.6 ohm. The conductivity of the solution (in S cm–1 where S has usual meaning) is

Detailed Solution for NEET Practice Test - 21 - Question 45
k = 1/R x Cell constant = 0.47/31.6

= 0.01487

NEET Practice Test - 21 - Question 46

A particle starting with certain initial velocity and uniform acceleration covers a distance of 12 m in the first 3 seconds and a distance of 30 m in the next 3 seconds. The initial velocity of the particle is

Detailed Solution for NEET Practice Test - 21 - Question 46
Let u be the initial velocity that have to be found and a be the uniform acceleration of the particle.

For t = 3s, distance travelled S = 12 m and for t = 3 + 3 = 6 s distance travelled

S '= 12 + 30 = 42 m

From, S = u t+ 1/2 at2

12 = u x 3 + 1/2 x a x 32

or 24 = 6u + 9a ..(i)

Similarly, 42 = u x 6 + 1/2 x a x 62

or 4 2 = 6u + 18a ..(ii)

On solving, we get u = 1 m s-1

NEET Practice Test - 21 - Question 47

When current in a coil changes from 5 A to 2 A in 0.1 s, average voltage of 50 V is produced. The self - inductance of the coil is

Detailed Solution for NEET Practice Test - 21 - Question 47
According to Faraday’s law of electro-magnetic induction,

Induced emf, e = Ldi/dt

= 1.67 H

NEET Practice Test - 21 - Question 48

The work function of aluminium is 4.2 eV. If two photons each of energy 3.5 eV strike an electron of aluminium, then emission of electron will

Detailed Solution for NEET Practice Test - 21 - Question 48
Work function of aluminium is 4.2 eV. The energy of two photons can not be added at the moment photons collide with electron all its energy will be dissipated or wasted as this energy is not sufficient to knock it out. Hence emission of electron is not possible.
NEET Practice Test - 21 - Question 49

Two wires A and B of the same material, having radii in the ratio 1 : 2 and carry currents in the ratio 4 : 1. The ratio of drift speed of electrons in A and B is

Detailed Solution for NEET Practice Test - 21 - Question 49
Current flowing through the conductor,

1 = nevdA. Hence

NEET Practice Test - 21 - Question 50

An object undergoing SHM takes 0.5 s to travel from one point of zero velocity to the next such point. The distance between those points is 50 cm. The period, frequency and amplitude of the motion is

Detailed Solution for NEET Practice Test - 21 - Question 50
Given: T/2 = 0.5 s

∴ T = 1s

Frequency, f = 1/T = 1/1 = 1Hz

If A is the amplitude, then

2 A = 50 cm ⇒ A = 25 cm.

NEET Practice Test - 21 - Question 51

A metallic bar is heated from 0ºC to 100ºC. The coefficient of linear expansion is 10–5 K–1. What will be the percentage increase in length?

Detailed Solution for NEET Practice Test - 21 - Question 51

= 10-1 = 0 . 1%

NEET Practice Test - 21 - Question 52

Plates of area A are arranged as shown. The distance between each plate is d, the net capacitance is

Detailed Solution for NEET Practice Test - 21 - Question 52
The equivalent circuit is shown in figure

Thus,

NEET Practice Test - 21 - Question 53

The heat radiated per unit area in 1 hour by a furnace whose temperature is 3000 K is (s = 5.7 × 10–8 W m–2 K–4)

Detailed Solution for NEET Practice Test - 21 - Question 53
According to Stefan’s law

E = σT4

Heat radiated per unit area in 1 hour (3600s) is

= 5.7x 108 x (3000)4 x 3600= 1.7 x 1010J

NEET Practice Test - 21 - Question 54

A gun fires two bullets at 60º and 30º horizontally. The bullets strike at some horizontal distance. The ratio of maximum height for the two bullets is in the ratio of

Detailed Solution for NEET Practice Test - 21 - Question 54
The bullets are fired at the same initial speed

=

= 3/1

NEET Practice Test - 21 - Question 55

Electric field inside a copper wire of length 10 metres, resistance 2 ohm connected to a 10 volt battery is

Detailed Solution for NEET Practice Test - 21 - Question 55

= 1 Vm-1

NEET Practice Test - 21 - Question 56

The path difference between the two waves

and will be

Detailed Solution for NEET Practice Test - 21 - Question 56
Phase difference = Φ

Path diff = λ / 2π x phase diff. = λ / 2πΦ

NEET Practice Test - 21 - Question 57

A body of mass 10 kg and velocity 10 m/s collides with a stationary body of mass 5 kg. After collision both bodies stick to each other, velocity of the bodies after collision will be

Detailed Solution for NEET Practice Test - 21 - Question 57
Velocity after the collision

=

= 100/15

= 20/3 m/sec.

NEET Practice Test - 21 - Question 58

The r.m.s. the velocity of an oxygen molecule at 16ºC is 474 m/sec. The r.m.s. velocity in m/s of hydrogen molecule at 127ºC is

Detailed Solution for NEET Practice Test - 21 - Question 58

so vH= 2230.59 m/sec

NEET Practice Test - 21 - Question 59

At 0ºK which of the following properties of a gas will be zero?

Detailed Solution for NEET Practice Test - 21 - Question 59
The kinetic energy is directly proportional to temperature.
NEET Practice Test - 21 - Question 60

If two soap bubbles of different radii are connected by a tube. Then

Detailed Solution for NEET Practice Test - 21 - Question 60
Let pressure outside be P0

∴ P1 ( in smaller bubble)

=

P2 (in bigger bubble)

=

∴ P1 > P2

Hence air moves from smaller bubbles to bigger bubbles.

NEET Practice Test - 21 - Question 61

A brass scale of a barometer gives correct reading at 0°C. αBrass = 0.00002/°C. The barometer reads 75 cm at 27°C. The atmospheric pressure at 0°C is

Detailed Solution for NEET Practice Test - 21 - Question 61
Suppose the correct barometer height at 0°C is (l0, then

l0 + Δl = 75

or l0 +75 x (αHgb) x 27 = 75

or l0 + 75 x (0.6 x 10-4 - 0.2 x 10-4) x 27 = 75

∴ l0 = 74.92 cm

NEET Practice Test - 21 - Question 62

For the velocity time graph shown in the figure below, the distance covered by the body in the last two seconds of its motion is what fraction of the total distance travelled by it in all the seven seconds?

Detailed Solution for NEET Practice Test - 21 - Question 62
Distance in last two second

= 1/2 x 10 x 2

= 10m.

Total distance = 1/2 x 10 x(6 + 2) = 40m

NEET Practice Test - 21 - Question 63

The dimensions of a × b in the relation E= b - x2 / at, where E is the energy, x is the displacement and t is time are

Detailed Solution for NEET Practice Test - 21 - Question 63
Here, b and x2 = L2 have same dimensions

Also,

a x b = [M-1L2T]

NEET Practice Test - 21 - Question 64

A particle undergoes simple harmonic motion having a time period T. The time taken in 3/8th oscillation is

Detailed Solution for NEET Practice Test - 21 - Question 64
Time to complete l/4th oscillation T/4s. Time to complete 1/8th vibration from extreme position is obtained from

So time to complete 3/8th oscillation

=

NEET Practice Test - 21 - Question 65

The given electrical network is equivalent to

:

Detailed Solution for NEET Practice Test - 21 - Question 65

i.e. NOR Sate

NEET Practice Test - 21 - Question 66

A doubly ionised Li atom is excited from its ground state(n = 1) to n = 3 state. The wavelengths of the spectral lines are given by λ32, λ31 and λ21. The ratio λ3231 and λ2131 are, respectively

NEET Practice Test - 21 - Question 67

A bullet of mass 5 g, traveling with a speed of 210 m/s, strikes a fixed wooden target. One half of its kinetics energy is converted into heat in the bullet while the other half is converted into heat in the wood. The rise of temperature of the bullet if the specific heat of its material is 0.030 cal/(g – ºC) (1 cal = 4.2 × 107 ergs) close to:

Detailed Solution for NEET Practice Test - 21 - Question 67
According to the question, one half of its kinetic energy is converted into heat in the wood.

= 87.5°C

NEET Practice Test - 21 - Question 68

ABC is an equilateral triangle. Charges +q are placed at each corner as shown in fig. The electric intensity at centre O will be

Detailed Solution for NEET Practice Test - 21 - Question 68
Unit positive charge at O will be repelled equally by three charges at the three corners of the triangle. By symmetry, resultant at O would be zero.
NEET Practice Test - 21 - Question 69

A rough vertical board has an acceleration along the horizontal so that a block of mass M pressing against it does not fall. The coefficient of friction between block and the board is

Detailed Solution for NEET Practice Test - 21 - Question 69

Force on M = Mg

Reaction force = Ma

force of friction = μR = μ.Ma

Force of friction will balance the weight. So

NEET Practice Test - 21 - Question 70

A plane wave of wavelength 6250 Å is incident normally on a slit of width 2 × 10–2 cm. The width of the principal maximum on a screen distant 50 cm will be

NEET Practice Test - 21 - Question 71

Two isolated conducting spheres S1 and S2 of radius 2/3R and 1/3R have 12 μC and -3μC charges, respectively, and are at a large distance from each other. They are now connected by a conducting wire. A long time after this is done the charges on S1 and S2 are respectively:

Detailed Solution for NEET Practice Test - 21 - Question 71
Total charge Q1 + Q2 = Q’1 + Q'2

= 12μC 3μC- 9μC

Two isolated conducting spheres S1 and S2 are now connected by a conducting wire.

NEET Practice Test - 21 - Question 72

A generator has an e.m.f. of 440 Volt and internal resistance of 400 Ohm. Its terminals are connected to a load of 4000 Ohm the voltage across the load is

Detailed Solution for NEET Practice Test - 21 - Question 72
Total resistance of the circuit = 4000 + 400 = 4400 Ω

Current flowing i = v/r = 440/4400 = 0.1 amp.

Voltage across load = Ri

= = 4000 x 0.1 = 400 volt.

NEET Practice Test - 21 - Question 73

A large number of liquid drops each of radius r coalesce to from a single drop of radius R. The energy released in the process is converted into kinetic energy of the big drop so formed. The speed of the big drop is (given, surface tension of liquid T, density r)

NEET Practice Test - 21 - Question 74

The diagram shows the energy levels for an electron in a certain atom. Which transition shown represents the emission of a photon with the most energy?

Detailed Solution for NEET Practice Test - 21 - Question 74

E will the maximum ibr the transition for which

is maximum. Here n2 is the higher energy level.

Clearly,

is maximum for the third transition,

i.e. 2 → 1 • I transition represents the absorption of energy.

NEET Practice Test - 21 - Question 75

Two particles of mass m1 and m2 (m1 > m2) attract each other with a force inversely proportional to the square of the distance between them. If the particles are initially held at rest and then released, the centre of mass will

Detailed Solution for NEET Practice Test - 21 - Question 75
The centre of mass remains at rest because force of attraction is mutual. No external force is acting.
NEET Practice Test - 21 - Question 76

The oscillating electric and magnetic field vectors of electromagnetic wave are oriented along

Detailed Solution for NEET Practice Test - 21 - Question 76
The direction of oscillations of E and B fields are perpendicular to each other as well as to the direction of propagation. So, electromagnetic waves are transverse in nature.
NEET Practice Test - 21 - Question 77

A uniform rod of mass m, length l , area of cross section A has Young’s modulus Y. If it is hanged vertically, elongation under its own weight will be