Try each question before opening its answer. Answer letters refer to the option order displayed here. A marked qualification identifies a source defect or a modelling assumption; see the explanation before scoring that item.
Biology
Question 1
IAT 2022 · BiologyMatch the features of a plant cell listed in Column I with their corresponding examples in Column II.
| Column I | Column II |
|---|
| i. Cell with cytoplasm and no nucleus | p. Pollen grain |
| ii. Cell lacking both cytoplasm and nucleus | q. Synergid |
| iii. Cell containing more than two nuclei | r. Tracheid |
| iv. Haploid cell produced by mitosis | s. Tapetum |
| t. Mature sieve tube |
| u. Phloem companion cell |
Choose the CORRECT combination from the options below.
i and u; ii and r; iii and s; iv and p
i and t; ii and r; iii and s; iv and q
i and ; ii and r; iii and q; iv and p
i and r; ii and t; iii and s; iv and q
Transcription note: Retyped the damaged matching table against the 2022 paper.
Answer & worked solution
Answer BA mature sieve-tube element retains cytoplasm but loses its nucleus, giving i–t. A mature tracheid is dead and lacks both, giving ii–r. Tapetal cells can be multinucleate, giving iii–s. Synergids develop by mitosis in the haploid female gametophyte, giving iv–q. The complete combination is therefore i–t, ii–r, iii–s, iv–q.
Question 2
IAT 2022 · Biology
Shown below are some of the reactions that occur in the metabolic pathway leading to complete oxidation of glucose during aerobic respiration.
i. Pyruvate Acetyl CoA
ii. Dihydroxy acetone phosphate Glyceraldehyde-3-phosphate
iii. Oxaloacetate Citrate
iv. Fumarate Malate
Choose the CORRECT sequence of reactions during the complete oxidation of glucose.
i; ii; iii; iv
i; iii; iv; ii
ii; i; iii; iv
ii; iii; i; iv
Transcription note: Removed repeated numerals in a distractor using the 2022 paper.
Answer & worked solution
Answer CPut the reactions in their metabolic order. Conversion of dihydroxyacetone phosphate to glyceraldehyde-3-phosphate occurs in glycolysis (ii). Pyruvate then forms acetyl-CoA (i). Acetyl-CoA enters the citric-acid cycle by combining with oxaloacetate to form citrate (iii); conversion of fumarate to malate occurs later in that cycle (iv). Thus the order is ii, i, iii, iv.
Question 3
IAT 2022 · BiologyIn a given species of flowering plant, the colour of the seeds is exclusively determined by the colour of its seed coat. Seed coat colour in this species is governed by a nuclear gene with two alleles. The WHITE ( ) allele is dominant over brown ( ) allele. If a plant with brown seeds is crossed as a female with pollen from a white seed plant, what will be the seed colour and the genotype of the embryo in the resultant seeds obtained from this cross?
Brown seeds with embryo
White seeds with embryo
Brown seeds with ww embryo
White seeds with ww embryo
Answer & worked solution
Answer AThe seed coat develops from the maternal integuments, so its genotype is that of the female parent,
, and its colour is brown. The embryo receives
from the mother and
from the father, making it
. Dominance in the embryo does not change the genotype of the maternal seed coat.
Question 4
IAT 2022 · BiologyDuring the CoVID-19 pandemic, SARS-CoV2 virus mutated multiple times giving rise to many variants. What is the genetic material of the SARS-CoV2 virus?
Single stranded RNA
Single stranded DNA
Double stranded RNA
Double stranded DNA
Answer & worked solution
Answer ASARS-CoV-2 has a single-stranded, positive-sense RNA genome. It is therefore an RNA virus; its genome is neither double-stranded DNA nor a DNA–RNA hybrid. The positive-sense RNA can serve as a template for translation after the virus enters a suitable host cell.
Question 5
IAT 2022 · BiologyLymph is an important body fluid. Choose the INCORRECT statement about the lymph.
Fat digested in the intestine is absorbed through the lymph.
It is the interstitial fluid generated by the passage of liquid between the cells of the capillary.
It is colourless and has similar mineral composition as of plasma.
It remains as an interstitial fluid and is never put back into circulation.
Answer & worked solution
Answer DLymph collects excess interstitial fluid, transports absorbed intestinal fats and carries immune cells. It ultimately drains into the venous circulation. It does not remain permanently in interstitial spaces: failure to return this fluid would cause swelling rather than normal fluid balance.
Question 6
IAT 2022 · BiologyInterneurons play an important role in the execution of spinal cord-mediated reflex action. Where are these interneurons located?
Dorsal root ganglion
White matter
Gray matter
Muscle spindle
Answer & worked solution
Answer CInterneurons connect neurons within the central nervous system and participate in local processing. Their cell bodies are associated with grey matter. Sensory neurons carry information toward the CNS, whereas motor neurons carry commands from it to effectors; neither description replaces the interneuron's integrating role.
Question 7
IAT 2022 · BiologyOsmoreceptors are sensitive to changes in ionic concentrations and volumes of body fluids. Which among the following best describes the function of these osmoreceptors?
They stimulate renin production to induce vasoconstriction and increase blood pressure
They stimulate pituitary gland to facilitate the secretion of mineralocorticoids to adjust the changes in mineral composition of the body fluid.
They stimulate atrial wall to release atrial natriuretic factor to induce vasodilation and reduce blood pressure.
They stimulate hypothalamus to facilitate the release of the anti-diuretic hormone and increase water reabsorption.
Answer & worked solution
Answer DAn increase in blood osmolarity stimulates hypothalamic osmoreceptors. This promotes release of antidiuretic hormone, ADH, from the posterior pituitary. ADH increases water permeability in the distal nephron, especially the collecting ducts, so more water returns to the blood and urine becomes more concentrated.
Question 8
IAT 2022 · BiologyA single point mutation in gene ' ' results in breathing difficulty, hypertension as well as partial sterility. Which among the following best explains the observed phenotypes?
Incomplete dominance
Pleiotropy
Linkage
Partial dominance
Answer & worked solution
Answer BPleiotropy means that one gene influences more than one phenotypic characteristic. A single altered protein may affect several tissues or pathways, producing multiple observable effects. This differs from polygenic inheritance, in which several genes contribute to one characteristic.
Question 9
IAT 2022 · BiologyIn a cross between individuals of the genotypes PpQQRrSS and ppqqRrSS, what will be the expected number of progenies with the genotype ppQQRrSS in a population of 400 individuals, assuming independent assortment?
0
25
100
200
Answer & worked solution
Answer AEvery gamete from a
parent carries
, and every gamete from a
parent carries
. Consequently every offspring is
. The dominant phenotype appears in all offspring, but the proportion with the homozygous dominant genotype
is zero.
Question 10
IAT 2022 · BiologyOrganisms in which of the following phyla are triploblastic, acoelomate and have bilateral symmetry?
Arthropoda
Mollusca
Platyhelminthes
Hemichordata
Answer & worked solution
Answer CPlatyhelminthes are triploblastic, bilaterally symmetrical animals with no body cavity between the body wall and gut: they are acoelomate. Arthropods and molluscs have a true coelom, often reduced with a prominent haemocoel, and hemichordates are coelomate. Therefore only Platyhelminthes has the complete combination requested.
Question 11
IAT 2022 · BiologyConsider the following biomes: Tropical Rainforest ; Tundra ; Desert and Coastal zone . The most probable order of Net Primary Productivity of these biomes is
Answer & worked solution
Answer BTropical rain forests (P) combine warmth, water and a long growing season, giving high net primary productivity. Productive coastal zones (S) follow in this broad comparison. Tundra (Q) is limited by a short cold growing season, and deserts (R) by severe water shortage. The expected order is therefore
. Actual site measurements vary, so this is the typical biome comparison used in the question.
Question 12
IAT 2022 · BiologyNine percent of a population cannot taste a certain food item because of a recessive allele of the gene IAT. Assuming the population is in Hardy-Weinberg equilibrium, what will be the frequency of dominant and recessive alleles, respectively?
0.7 and 0.3
0.9 and 0.1
0.3 and 0.7
0.1 and 0.9
Answer & worked solution
Answer AUnder Hardy–Weinberg equilibrium, the recessive phenotype has frequency
. Here
, so
and
. The dominant and recessive allele frequencies are therefore
and
, respectively; it should not be confused with the dominant phenotype frequency
.
Question 13
IAT 2022 · BiologyAs opposed to DNA replication within the cell, discontinuous synthesis of DNA does NOT occur in a polymerase chain reaction (PCR). Why?
The replication fork is formed and DNA ligase activity of the Taq polymerase joins the discontinuous fragments.
The replication fork is formed and Taq polymerase extends DNA in both to and to direction.
Denaturation step in PCR substitutes for the replication fork and Taq polymerase extends DNA only in the to direction.
Denaturation step in PCR substitutes for the replication fork and Taq polymerase extends DNA only in the to direction.
Answer & worked solution
Answer DPCR first separates the DNA strands by heating. After primers bind, thermostable DNA polymerase extends each primer continuously in the
direction along its available template. There is no advancing replication fork requiring repeated lagging-strand priming, so Okazaki fragments are not an intrinsic part of PCR amplification.
Question 14
IAT 2022 · BiologyWhich of the following figures CORRECTLY represents the chemiosmotic hypothesis of ATP synthesis occurring in a mitochondrion in a cell? (Keys for the figure; IMS: Intermembrane space, IMM: Inner mitochondrial membrane, MM: Mitochondrial matrix, ETC: Electron transport chain)
Answer & worked solution
Answer DThe respiratory electron-transport chain pumps protons from the mitochondrial matrix into the intermembrane space. Protons then return to the matrix through ATP synthase; its catalytic head faces the matrix. Only the diagram in D has both the transport direction and ATP-synthase orientation consistent with this chemiosmotic arrangement.
Question 15
IAT 2022 · BiologyLet 'X' be the perpendicular distance from the centromere of each chromosome to the equatorial plane of a human cell. Which of the following stages of the cell cycle is most likely to have the HIGHEST average value of 'X'?
Early anaphase
Early metaphase
Late anaphase
Metaphase
Transcription note: Normalised quotation marks around X; this is a distance, not a derivative.
Answer & worked solution
Answer CDuring metaphase, chromosomes align near the equatorial plane. In anaphase the separated sister chromatids, now daughter chromosomes, move toward opposite poles. Their centromeres are therefore farthest from the equator among the stages listed in late anaphase, making the average distance
largest then.
Chemistry
Question 1
IAT 2022 · ChemistryThe products of the reaction between aqueous solutions of and are
and KOH
and
K3[Fe(CN)6], H2O and O2
and HCN
Transcription note: Restored O2 in the distractor from the 2022 paper.
Answer & worked solution
Answer AIron changes from
in ferrocyanide to
in ferricyanide, releasing one electron per complex. Half a mole of peroxide accepts that electron in the alkaline balance. The net equation is
. Both the potassium count and the hydrogen/oxygen counts balance.
Question 2
IAT 2022 · ChemistryFor the colourless complex , where is a transition metal, the CORRECT ground state -electron configuration of is
Answer & worked solution
Answer BA
ion has all five
orbitals filled. In an octahedral field its configuration is
. There is no vacant
level available for an ordinary
–
excitation, explaining the colourless aqua complex within the options. The other listed configurations have partially filled
shells.
Question 3
IAT 2022 · ChemistryChoose the correct statement about the structure of fullerene
6-membered rings are fused with 5-membered rings ONLY.
6-membered rings are fused with 6-membered rings ONLY.
5-membered rings are fused with 6-membered rings ONLY.
5-membered rings are fused with both 5-membered and 6-membered rings.
Answer & worked solution
Answer CThe
cage contains 12 pentagons and 20 hexagons. Its pentagons are isolated: each pentagon shares its edges with hexagons, not with other pentagons. Hexagons border both pentagons and hexagons. Thus the statement that five-membered rings are fused only with six-membered rings is correct.
Question 4
IAT 2022 · Chemistry
1,4
3,4
3,5
4,5
Answer & worked solution
Answer BLook for the sudden rise after all valence electrons have been removed. For X, the jump from the third to fourth ionisation energy indicates three valence electrons. For Y, the jump from the fourth to fifth indicates four. The required pair is therefore
.
Question 5
IAT 2022 · ChemistryWhich of the following expressions represents the hydrogen atom wave function shown in the figure below? ( is the distance of the electron from the nucleus and is a constant)

Answer & worked solution
Answer CThe plotted wavefunction is nonzero at the nucleus, crosses zero once, then approaches zero from below. A
orbital has exactly this radial behaviour:
, with its node at
. A
function never changes sign, while a
function vanishes at the nucleus.
Question 6
IAT 2022 · Chemistry

M and O only
N and P only
M, N and O only
M, N, O, and P
Answer & worked solution
Answer CM is pyridine, with six ring
electrons. Protonation of its external nitrogen lone pair gives N without removing the six-electron aromatic circuit. In O, pyrrole's nitrogen lone pair contributes two electrons to the four from the double bonds. Protonating that lone pair in P interrupts the aromatic circuit. Hence M, N and O are aromatic, but P is not.
Question 7
IAT 2022 · ChemistryWhich of the following are aryl bromides?

N and P only
N and O only
M, O and P only
N, O and P only
Answer & worked solution
Answer AAn aryl bromide has bromine bonded directly to a carbon of an aromatic ring. N and P satisfy this definition. A bromine on a side chain is an alkyl or benzylic bromide instead, and the brominated saturated carbon in M is not an aromatic ring carbon. Therefore only N and P qualify.
Question 8
IAT 2022 · ChemistryBenzamide is treated with and to form the product , which is then reacted with and at to form . is immediately treated with ethanol to give . What is Z?
Answer & worked solution
Answer DBromine and aqueous base convert benzamide to aniline by Hofmann rearrangement, losing the carbonyl carbon. Cold nitrous acid then converts aniline into a benzenediazonium salt. Ethanol reduces the diazonium group to hydrogen, releasing nitrogen. The final aromatic product is benzene.
Question 9
IAT 2022 · Chemistry

Answer & worked solution
Answer BBase first forms phenoxide, which reacts with methyl iodide by
substitution to produce anisole M. Its methoxy group activates the ring and directs Friedel–Crafts acetylation mainly to the para position, giving N. Hypochlorite then causes the haloform oxidation of the methyl ketone to the para-methoxybenzoate salt O. This sequence is shown in B.
Question 10
IAT 2022 · ChemistryThe van der Waals equation for a real gas is given by . What is the dimension of ?
Answer & worked solution
Answer DThe correction
must have the dimensions of pressure, so
. Also
. Hence
, the dimensions of energy. This uses dimensional consistency of the equation, without assigning numerical values to either constant.
Question 11
IAT 2022 · Chemistry

Answer & worked solution
Answer AWithout a peroxide initiator, HBr adds by the ionic pathway. Proton addition that leaves a benzylic carbocation is favoured because the positive charge is resonance-stabilised by the phenyl ring. Bromide captures that carbocation, placing Br on the carbon directly attached to the ring, as shown in A.
Question 12
IAT 2022 · ChemistryAn aqueous solution contains 1.0 M of and 0.001 M of ions at and ions do not interact with each other. This solution is put in an electrolytic cell and the voltage is gradually increased till a current begins to flow through the cell. The voltage is maintained at this point and a deposit is observed on the cathode. What is the composition of the material deposited on the cathode?
(Given: Atomic weight of is 63 and is 200.)
( is the standard reduction potential.)
Only Y
and by weight
Only X
and by weight
Answer & worked solution
Answer CUse the actual concentrations in the Nernst equation, not just the standard potentials. For X,
V because
M. For Y,
V. X has the higher reduction potential under these conditions and begins depositing first. At the threshold specified, the deposit is only X.
Question 13
IAT 2022 · Chemistry2 g of naphthoic acid (molecular weight ) dissolved in 20 mL of benzene shows a freezing point depression of 2 K . For benzene, the freezing point depression constant, and the density is . What is the magnitude of the van't Hoff factor?
0.605
605.0
0.688
688.0
Answer & worked solution
Answer AThe solvent mass is
g, or
kg. The solute amount is
mol, so
. From
,
. The value below one is consistent with association of acid molecules in benzene.
Question 14
IAT 2022 · ChemistryFor the reaction involving ideal gases, , which of the following plots is qualitatively correct? ( and are the equilibrium constants in terms of pressure and concentration respectively. is the absolute temperature.)
Answer & worked solution
Answer DFor
, the change in gaseous mole number is
. Therefore
. As a function of absolute temperature this is an upward-curving quadratic through the origin, matching D. This conclusion concerns the ratio, even though each equilibrium constant may have a more complicated temperature dependence.
Question 15
IAT 2022 · ChemistryIdentify the correct order of the molecules with respect to the magnitude of their dipole moment:
Transcription note: Restored the para-difluoro structure from the 2022 paper; the secondary diagram showed different para substituents.
Answer & worked solution
Answer CThe para-difluoro compound has zero dipole moment by symmetry. Meta-dichlorobenzene has a smaller resultant than its ortho isomer because its substituent dipoles are farther apart in angle. The ortho-difluoro compound is slightly more polar than ortho-dichlorobenzene in the ordering used here, giving para-difluoro < meta-dichloro < ortho-dichloro < ortho-difluoro. The first structure in C has been restored to para-difluorobenzene from the paper; a secondary diagram incorrectly showed unlike para substituents. Electronegativity alone is not a reliable numerical rule for comparing molecular dipole moments.
Mathematics
Question 1
IAT 2022 · MathematicsA randomly chosen card from a deck of 52 cards is given to be a black card (Spade or Club). What is the probability that it is either a face card (King, Queen or Jack) or a Spade?
9/13
Answer & worked solution
Answer BCondition on the 26 black cards. There are 13 spades and six black face cards, but three cards belong to both groups. The favourable count is
. Thus the conditional probability is
.
Question 2
IAT 2022 · Mathematics
Let be a complex root of the quadratic polynomial . The value of
is
Answer & worked solution
Answer CSince
and
, each factor is
when its exponent is divisible by 3 and
otherwise. Among 1 through 100 there are 33 multiples of 3 and 67 other integers. The product is
.
Question 3
IAT 2022 · MathematicsLet be a polynomial. Suppose that ,
and
Then
25
35
55
105
Answer & worked solution
Answer CIf a polynomial has degree at least three, its third and fifth derivatives cannot be identical nonzero polynomials because their degrees differ. The identity therefore forces its degree to be at most two. Write
. The initial data give
,
and
, so
.
Question 4
IAT 2022 · MathematicsLet be the set of all unit vectors in the -plane. Then the set has
8 elements
2 elements
4 elements
Infinitely many elements
Answer & worked solution
Answer DEvery angle
defines a unit vector
in the plane. As
ranges continuously over
, these give infinitely many distinct vectors. Restricting to the coordinate-axis directions would omit almost all of the unit circle.
Question 5
IAT 2022 · MathematicsA lab reports that the global average temperature in the year 2020 was and predicts that the global average temperature will increase at the rate of per year. What will be the global average temperature in the year 2035?
Answer & worked solution
Answer B · qualification belowThis is the stipulated numerical growth model, not a physical climate model.
Annual growth by 1% multiplies the reported numerical temperature by
each year. There are 15 years from 2020 to 2035, so the stipulated model gives
, closest to B. This is the mathematical model stated in the question; percentage change of Celsius temperature is scale-dependent and is not a physical climate model.
Question 6
IAT 2022 · MathematicsLet be the set of all matrices with real entries and be the relation . Which of the following statements is true?
is reflexive and symmetric but not transitive
is reflexive and transitive but not symmetric
is symmetric and transitive but not reflexive
is an equivalance relation
Answer & worked solution
Answer AEvery matrix commutes with itself, so the relation is reflexive. If
, the same equation proves symmetry. Transitivity fails: let
,
, and
. Both A and C commute with B, but
and
.
Question 7
IAT 2022 · MathematicsFor a natural number
, let
be the curve in the XY-plane given by
, where
. Let
denote the area of the region bounded between
and
. Then the largest value of
is
Transcription note: Restored the subscript n+1 from the paper.
Answer & worked solution
Answer C · qualification belowNatural numbers are taken to begin at 1, as intended by the paper.
On
,
. Hence
. For natural numbers starting at 1, this decreases with n and is largest at
, giving
. Including zero in the convention for natural numbers would change the answer to
; the paper uses the positive-integer convention.
Question 8
IAT 2022 · MathematicsLet be a continuous function on and be its antiderivative. If and , then is
0
1
2
Answer & worked solution
Answer DThe fundamental theorem of calculus gives
. Since
, it follows that
. The additive constant in an antiderivative is fixed by the initial value.
Question 9
IAT 2022 · MathematicsLet be a nonzero real number and be a continuous function such that for all . Consider . Then has
Local maxima at if
Local maxima at if
Local minima at if
A point of inflection at
Answer & worked solution
Answer AThe condition
makes f strictly increasing, so it preserves the location and type of extrema of its inner argument. Write
. If
, this has a strict maximum at
; if
, it has a minimum there. Thus A is the true statement.
Question 10
IAT 2022 · MathematicsLet be the matrix . For any natural number , the determinant of is
0
1
-1
Answer & worked solution
Answer BExpand the determinant along the second column:
. Determinants multiply under matrix products, so
for every positive integer k.
Question 11
IAT 2022 · MathematicsConsider the vectors . The values of for Which there is at least one nonzero vector perpendicular to the vectors and are
0,2
Answer & worked solution
Answer AA nonzero vector perpendicular to all three exists precisely when the three vectors do not span
. Set their scalar triple product to zero:
. Therefore
or
.
Question 12
IAT 2022 · MathematicsConsider the tangent lines to the circle at points and . If is the point of intersection of these two tangent lines, then is:
Answer & worked solution
Answer BThe radii OP and OQ subtend
at the centre. Each radius is perpendicular to its tangent, so in quadrilateral OPRQ the two angles at P and Q are right angles. Hence
.
Question 13
IAT 2022 · MathematicsThe function given by is
Increasing on the interval
Decreasing on the interval
Increasing on the interval
Decreasing on the interval
Answer & worked solution
Answer ADifferentiate:
. It is positive for
and
, and negative for
. Thus the function is increasing throughout
, while each of the other descriptions has the wrong sign.
Question 14
IAT 2022 · MathematicsThe value of the integral
where is the greatest integer less than or equal to for any real number , is
Answer & worked solution
Answer DOn
, the floor function is k. Thus the integral equals
. Collecting the logarithms gives
. Values at isolated integer endpoints do not change the integral.
Question 15
IAT 2022 · MathematicsFor arbitrary constants , the differential equation representing the family of curves is
Answer & worked solution
Answer AMultiply the family by
to get
. Its second derivative is zero. Differentiating twice gives
, so the required differential equation is
.
Physics
Question 1
IAT 2022 · PhysicsA particle experiences an acceleration , where is the velocity of the particle and is a constant. If the distances traveled by the particle in the time intervals and are and , respectively, which of the following relations is true?
Answer & worked solution
Answer CSolving
from time
gives
. The direction stays fixed, so integrating the speed gives
. Taking the ratio cancels the prefactor and yields C. For
, interpret the expression by its constant-speed limit.
Question 2
IAT 2022 · PhysicsA point mass attached to a massless string is undergoing circular motion in a vertical plane. The length of the string is and the acceleration due to gravity is . If the minimum value of the tension in the string is 2 mg , the maximum speed of this circular motion of the point mass is
Answer & worked solution
Answer BTension is smallest at the top. There,
, so
. Falling through height
to the bottom adds
to the squared speed by energy conservation. Hence the maximum speed is
.
Question 3
IAT 2022 · PhysicsAn object is released from rest from the inner edge of a hemispherical bowl, and it falls under gravity. The coefficient of kinetic friction between the object and the bowl is . If the object covers an angular displacement with respect to the center of the hemisphere when it stops for the first time, which of the following expressions is correct?
Answer & worked solution
No valid listed optionNone of the options gives the exact sliding-bowl result with the full normal reaction.
The advertised relation
, option B, results from omitting the centripetal contribution to the normal force. It is not the exact sliding-bowl result. Let
be the angle travelled from the rim and
. The normal reaction is
, giving
. With
,
. The first positive zero determines the stopping angle. No listed expression gives this relation in general; B is the source's intended simplified answer, not an exact consequence of the stated mechanics.
Question 4
IAT 2022 · PhysicsAs shown in the figure a block is resting on a frictionless floor and is attached to the free end of a spring. The right edge of the block in equilibrium is at a distance
from the wall. When the spring is compressed by a distance
and released, the time-period of the motion is
. Similarly, when compressed by a distance
and released, the time-period is
. Considering elastic collision between the block and the wall, what is the value of the quantity
?

1
Answer & worked solution
Answer DWith the smaller amplitude, the block never reaches the wall and
. For amplitude
, set
, measured from equilibrium. It first hits the wall at
, so
. The elastic rebound retraces the motion to
in the same time. Thus
and
.
Question 5
IAT 2022 · PhysicsA liquid of density
in a container weighs
. A cubic block of side
and density
is pushed by a stick to completely submerge the block in the liquid without touching the bottom. If
is the acceleration due to the gravity and liquid displaced by the stick is negligible, what is the new weight of the container as registered by the weighing machine below?

Answer & worked solution
Answer AA fully submerged block displaces volume
, so the liquid exerts buoyancy
upward on it. The block exerts an equal downward force on the liquid. Therefore the scale reading increases by
, giving
. The externally held stick supplies the additional force needed to keep the light block submerged.
Question 6
IAT 2022 · PhysicsA monoatomic ideal gas at pressure and volume is first adiabatically compressed to volume and then is allowed to expand isothermally back to its original volume. What is the final pressure of the gas?
Answer & worked solution
Answer CFor a monatomic ideal gas,
. Adiabatic compression gives
. The subsequent expansion is isothermal at
. Once the volume returns to V, the ideal-gas law gives the final pressure
.
Question 7
IAT 2022 · PhysicsA uniform taut string with two point charges
and
attached to its ends passes over two massless pullies kept
distance apart as shown in the fgure. If
is the fundamental frequency of the part of the string over pullies, which of the following statements is correct?

Answer & worked solution
Answer AThe charge separation shown is proportional to L, so Coulomb attraction, and therefore the string tension, scales as
. For constant linear mass density, wave speed scales as
. The fundamental frequency of the segment is
, giving
.
Question 8
IAT 2022 · PhysicsTwo uniformly charged concentric thin spherical shells of radii
and
have charges
and
, respectively. How does the electrostatic potential vary with distance from the center of the shells?

Answer & worked solution
Answer BChoose zero potential at infinity. Outside the outer shell the total enclosed charge is zero and
. Between the shells,
, which decreases continuously to zero. Inside the inner shell,
is constant. The potential cannot jump at either thin shell, so B gives the appropriate qualitative graph.
Question 9
IAT 2022 · PhysicsConsider a very long cylinder of radius having a uniform positive charge density . A sphere of radius has been carved out (see figure), leaving no charge in that region. The distance radially outward to the cylinder, as measured from the center of the sphere is . At what value of will the electric field be maximum?

Answer & worked solution
Answer DSuperpose the full charged cylinder and a negatively charged sphere representing the cavity. Inside the cavity,
, which increases. For
,
. Setting its derivative to zero gives
, hence
. The derivative changes from positive to negative there.
Question 10
IAT 2022 · PhysicsConsider that in a fission of a single Plutonium ( ) atom 207 MeV energy is released. Assuming all atoms of Plutonium undergo fission, which of the following options is the closest estimate of the amount of Plutonium required for a 20,000 units of TNT explosion? (1 unit of TNT )
60.0 g
0.5 kg
1 kg
10 kg
Answer & worked solution
Answer CThe total energy in the stated comparison is
J. Divide by the stipulated energy per fission,
J, to obtain
atoms. Using 239 g per mole gives about
g. Thus 1 kg is the closest estimate under the question's assumption that every atom fissions.
Question 11
IAT 2022 · PhysicsIn the given circuit, the box
either contains a capacitor, or an inductor or a resistor. The current
versus time
plots for three cases
are shown in figures. The switch
is closed at time
. Which of the following is correct?

corresponds to an inductor, corresponds to a capacitor, correspond to a resistor.
corresponds to a resistor, corresponds to an inductor, corresponds to capacitor
corresponds to an inductor, corresponds to a resistor, corresponds to capacitor.
corresponds to a resistor, corresponds to a capacitor, corresponds to inductor.
Answer & worked solution
Answer DA resistor produces an immediate constant current, matching
. A capacitor initially conducts while charging, after which the current decays to zero, matching
. An inductor initially opposes the change in current, which then rises toward its steady value, matching
. Hence D gives the correct correspondence.
Question 12
IAT 2022 · PhysicsIn the given circuit each of the resistors is of
resistance and each of the capacitors has
capacitance. What is the charge in the capacitor between the points B and F ?

Answer & worked solution
Answer AAt DC steady state, all capacitors are open circuits. The conducting path from A to D contains four equal resistors: AB, BC, CG and HD, with G and H joined by wire. Taking
and
V gives
V and
V. The unpowered resistor branch through E and F carries no current, so
. Thus
.
Question 13
IAT 2022 · PhysicsA thin lens made of material of refractive index
forms the image at the position I of a point object held at O on the central axis of the lens, as is shown in the ray diagram below. Consider that the refractive index of the medium is
and
for the figure given. Where does the image form when
?

At point A
At point B
At point
At point D
Transcription note: Restored the missing ray diagram and damaged inequality from the 2022 paper. This is Physics question 12 in that PDF; numbering here follows the supplied year-wise collection.
Answer & worked solution
Answer B · qualification belowThe image lies between object and lens; exact distance requires additional refractive-index data.
The lens-maker factor is
. When the surrounding medium becomes optically denser than the lens, this factor changes sign, so the biconvex lens becomes diverging. A real object then produces an upright virtual image on the object side, between the object and the lens. The marked point in that region is B. The exact position depends on the new refractive indices, which are not numerically specified.
Question 14
IAT 2022 · PhysicsA conducting sphere of radius
initially contains a uniform volume charge density
. What is the electric flux
through a spherical surface of radius
centered at a point on the surface of the charged sphere (see figure) at a later time
? (
is the permittivity of free space.)

Answer & worked solution
Answer BThe displaced Gaussian sphere encloses the entire charged conducting sphere, including its surface after charge redistribution. The conserved enclosed charge is
. Gauss's law therefore gives
. Changing the internal charge distribution does not change the total flux through a surface enclosing all the charge.
Question 15
IAT 2022 · PhysicsThe figures in the options show the photocurrent of a photoelectric material versus the frequency of an incident light beam. The light beam can have three different intensities , with . Which of the options is correct?
Answer & worked solution
Answer A · qualification belowThe horizontal branches are schematic; current need not be frequency-independent at fixed power.
The threshold frequency is fixed by the material's work function and is the same for all intensities. Above threshold, a greater intensity gives a greater photocurrent under otherwise identical collection conditions. A is the only sketch with both features. Its perfectly flat branches are a simplified qualitative convention: at fixed optical power and quantum efficiency the photon rate is
, so actual current need not be exactly independent of frequency.