- a$p\ne 0,\ q=0$
- b$p=0,\ q=0$
- c$p\ne 0,\ q\ne 0$
- d$p=0,\ q\ne 0$
Answer (a): A fraction is undefined exactly when its denominator is zero, so $q=0$ with $p\ne 0$ gives an undefined value.
Revise: Algebra (Class 11 notes)
TU IOST | Entrance paper
Answer (a): A fraction is undefined exactly when its denominator is zero, so $q=0$ with $p\ne 0$ gives an undefined value.
Revise: Algebra (Class 11 notes)
Answer (a): Square brackets mean both end points are included, so the closed interval is $a\le x\le b$.
Revise: Algebra (Class 11 notes)
Answer (a): For $x=-3$, $f(-3)=\sqrt{4-9}=\sqrt{-5}$, which is not real. Since $f:R\to R$, the function is undefined at $-3$.
Revise: Algebra (Class 11 notes)
Answer (c): $|x|=1$ means $x=1$ or $x=-1$.
Revise: Algebra (Class 11 notes)
Answer (d): $x-7=2^1=2$, so $x=9$.
Revise: Algebra (Class 11 notes)
Answer (b): If $\cos\theta=4/5$ then $\sin\theta=\sqrt{1-16/25}=3/5$.
Revise: Trigonometry (Class 11 notes)
Answer (c): $\tan x=\pm\sqrt3$, which is $\tan^2x=\tan^2\frac\pi3$, so $x=n\pi\pm\frac\pi3$.
Revise: Trigonometry (Class 11 notes)
Answer (c): In an AP $2b=a+c$: $2(4k-6)=(k+2)+(3k-2)=4k$, so $8k-12=4k$ and $k=3$.
Revise: Algebra (Class 11 notes)
Answer (b): GP with $a=1$, $r=-1/2$: $S=\frac{a}{1-r}=\frac{1}{3/2}=\frac23$.
Revise: Algebra (Class 11 notes)
Answer (d): A $3\times1$ matrix times a $1\times3$ matrix is $3\times3$ with entries $a_ib_j$, giving the matrix in option d.
Revise: Algebra (Class 11 notes)
Answer (c): Row 3 is $4$ times row 2, so two rows are proportional and the determinant is $0$.
Revise: Algebra (Class 11 notes)
Answer (b): The entries satisfy $a_{ij}=a_{ji}$ (2,3 and 3,4), so the matrix equals its transpose.
Revise: Algebra (Class 11 notes)
Answer (a): By De Moivre: $2^6(\cos90^\circ+i\sin90^\circ)=64i$.
Revise: Algebra (Class 11 notes)
Answer (c): $1+\omega+\omega^2=0$ and $1+\omega=-\omega^2$, so the second bracket is $-2\omega^2$; its cube is $-8\omega^6=-8$.
Revise: Algebra (Class 11 notes)
Answer (a): Sum $=-1$, product $=-6$, so $x^2-(-1)x+(-6)=x^2+x-6=0$.
Revise: Algebra (Class 11 notes)
Answer (a): Slopes are $-k/3$ and $5/2$. Perpendicular: $(-k/3)(5/2)=-1$, so $k=6/5$.
Revise: Analytic geometry (Class 11 notes)
Answer (d): Pair of lines $ax^2+2hxy+by^2=0$ is perpendicular when $a+b=0$: $5+k=0$, so $k=-5$.
Revise: Analytic geometry (Class 11 notes)
Answer (a): Tangent at $(x_1,y_1)$ is $xx_1+yy_1=r^2$: $x+y=2$.
Revise: Analytic geometry (Class 11 notes)
Answer (d): Divide by $x^2$: the limit is the ratio of leading coefficients, $3/6=\frac12$.
Revise: Calculus (Class 11 notes)
Answer (a): Using $1-\cos ax=2\sin^2\frac{ax}{2}$, the limit is $2\cdot\frac{a^2}{4}=\frac{a^2}{2}$.
Revise: Calculus (Class 11 notes)
Answer (b): $dy/dt=\sin t$, $dx/dt=1+\cos t$, so $dy/dx=\frac{2\sin\frac t2\cos\frac t2}{2\cos^2\frac t2}=\tan\frac t2$.
Revise: Calculus (Class 11 notes)
Answer (a): $\frac{d(\cos x)}{d(\sin x)}=\frac{-\sin x}{\cos x}=-\tan x$.
Revise: Calculus (Class 11 notes)
Answer (c): $y''=6x-24=0$ gives $x=4$, and $y''$ changes sign there.
Revise: Calculus (Class 11 notes)
Answer (b): $\int\csc^2x,dx=-\cot x+C$.
Revise: Calculus (Class 11 notes)
Answer (a): $\tan^{-1}x\Big|_0^1=\frac\pi4-0=\frac\pi4$.
Revise: Calculus (Class 11 notes)
Answer (b): The word is stressed as com-MEM-o-rate, on the second syllable.
Revise: Grammar and Usage (Class 11 notes)
Answer (c): 'Go' has the vowel /əʊ/, the same as 'sew'. 'Nor' and 'four' have /ɔː/ and 'tour' has /ʊə/.
Revise: Grammar and Usage (Class 11 notes)
Answer (b): A school does not open itself, so the passive is needed, and it follows "hope that" in the present form: "is opened".
Revise: Grammar and Usage (Class 11 notes)
Answer (a): "Bellicose" describes a person eager to fight.
Revise: Vocabulary and Word Formation (Class 11 notes)
Answer (b): Ominous means threatening; the opposite is auspicious (promising).
Revise: Vocabulary and Word Formation (Class 11 notes)
Answer (a): Idiom: die of a disease, die from (loss of blood) an injury or cause.
Revise: Grammar and Usage (Class 11 notes)
Answer (d): The verb 'give' takes 'to' for the recipient: Whom did you give it to?
Revise: Grammar and Usage (Class 11 notes)
Answer (a): "Spring upon" means to leap at and attack.
Revise: Grammar and Usage (Class 11 notes)
Answer (c): Rice and curry is thought of as one single dish, so the verb is singular: "is".
Revise: Grammar and Usage (Class 11 notes)
Answer (a): A snag is a hidden difficulty, that is, a drawback.
Revise: Vocabulary and Word Formation (Class 11 notes)
Answer (b): Polygamy is having many spouses; bigamy is exactly two.
Revise: Vocabulary and Word Formation (Class 11 notes)
Answer (b): Monkeys gibber (chatter rapidly). Growl, yelp and howl belong to other animals such as dogs and wolves.
Revise: Vocabulary and Word Formation (Class 11 notes)
Answer (d): "To his sister" names the receiver of the book, so it is the indirect object.
Revise: Grammar and Usage (Class 11 notes)
Answer (a): A possessive determiner is needed before 'hood', so 'its'. 'It's' means 'it is'.
Revise: Grammar and Usage (Class 11 notes)
Answer (c): "The same" is a fixed phrase.
Revise: Grammar and Usage (Class 11 notes)
Answer (b): Versatile means able to do many things well, so gifted fits best.
Revise: Vocabulary and Word Formation (Class 11 notes)
Answer (a): The standard word is "non-aggression".
Revise: Vocabulary and Word Formation (Class 11 notes)
Answer (b): Pyro means fire, so pyrophobia.
Revise: Vocabulary and Word Formation (Class 11 notes)
Answer (d): "Reality" is formed with the noun suffix -ity; the others are adjectives.
Revise: Grammar and Usage (Class 11 notes)
Answer (b): "Until" links waiting with the time the bus came.
Revise: Grammar and Usage (Class 11 notes)
Answer (a): Itinerant means moving from place to place, especially for work.
Revise: Vocabulary and Word Formation (Class 11 notes)
Answer (a): Positive statement takes a negative tag: "aren't you".
Revise: Grammar and Usage (Class 11 notes)
Answer (b): An alternative question rises on the first option and falls on the last.
Revise: Grammar and Usage (Class 11 notes)
Answer (b): Atomic radii are about $1$ angstrom, i.e. $10^{-10}$ m.
Revise: Physical Quantities (Class 11 notes)
Answer (c): The distance from the earth is greatest when the maximum height is greatest, $H=u^2\sin^2\theta/2g$, which occurs at $90^\circ$. The $45^\circ$ angle only maximizes horizontal range.
Revise: Kinematics (Class 11 notes)
Answer (a): Air friction dissipates its energy, damping the oscillation.
Revise: Periodic Motion (Class 12 notes)
Answer (c): Attraction between unlike molecules (powder and skin) is adhesion.
Revise: Elasticity (Class 11 notes)
Answer (c): Viscosity arises from momentum transfer between adjacent layers of a fluid moving at different speeds, so it is most closely related to transfer of momentum.
Revise: Fluid Statics (Class 12 notes)
Answer (d): $\Delta L=L\alpha\Delta T=700\times11\times10^{-6}\times(243-131)=700\times11\times10^{-6}\times112=0.8624$ m, which is 86.24 cm.
Revise: Thermal Expansion (Class 11 notes)
Answer (b): Internal energy of an ideal gas depends only on temperature, which is constant in an isothermal process.
Revise: First Law of Thermodynamics (Class 12 notes)
Answer (a): Real steam engines convert only a small fraction of heat to work, of the order of 10 percent.
Revise: Second Law of Thermodynamics (Class 12 notes)
Answer (b): For the same initial state and the same final volume, an isobaric expansion keeps pressure at its highest value, so its area under the P-V curve is larger than for isothermal or adiabatic expansion.
Revise: First Law of Thermodynamics (Class 12 notes)
Answer (a): A large resultant amplitude comes from constructive interference.
Revise: Interference (Class 12 notes)
Answer (d): $f'=f\frac{v+v_o}{v}=524\times\frac{345}{340}\approx531.7\approx532$ Hz.
Revise: Acoustic Phenomena (Class 12 notes)
Answer (d): In a longitudinal wave the particles oscillate along the direction of propagation, moving both forward and backward, so parallel or anti-parallel.
Revise: Wave Motion (Class 12 notes)
Answer (c): $E=I/r^2=100/4=25$ lux.
Revise: Nature and Propagation of Light (Class 12 notes)
Answer (d): White light is bent (deviated) and split into colours (dispersed).
Revise: Refraction Through Prisms (Class 11 notes)
Answer (a): $n=1/\sin C=1/\sin30^\circ=2$.
Revise: Refraction at Plane Surface (Class 11 notes)
Answer (a): $n=Q/e=1/(1.6\times10^{-19})=6.25\times10^{18}$.
Revise: Electric Charges (Class 11 notes)
Answer (b): Heating lowers the density, so light travels faster and the refractive index decreases.
Revise: Refraction at Plane Surface (Class 11 notes)
Answer (c): $\tau=pE\sin\theta$, proportional to the product of $p$ and $E$.
Revise: Electric Field (Class 11 notes)
Answer (d): The bridge balances ratios of resistances to find an unknown resistance.
Revise: Electrical Circuit One (Class 12 notes)
Answer (d): Above the Curie temperature a ferromagnet turns paramagnetic and loses its magnetism.
Revise: Magnetic Properties of Materials (Class 12 notes)
Answer (a): $\Phi=LI=10\times10^{-3}\times2=0.02$ Wb.
Revise: Electromagnetic Induction (Class 12 notes)
Answer (c): Positive rays are streams of positive ions.
Revise: Electrons (Class 12 notes)
Answer (d): $E=\frac{12375}{4000}\text{ eV}\approx3.09$ eV.
Revise: Photons (Class 12 notes)
Answer (b): $r_n=n^2a_0$.
Revise: Quantization of Energy (Class 12 notes)
Answer (a): At very low temperatures carriers freeze out in semiconductors, so they stop conducting.
Revise: Semiconductor Devices (Class 12 notes)
Answer (a): $25/100=0.25$ mol, and each formula unit has one C: $0.25\times6.022\times10^{23}=1.505\times10^{23}$.
Revise: Stoichiometry (Class 11 notes)
Answer (a): Half-filled $d$ subshell is extra stable, so one $4s$ electron moves to $3d$.
Revise: Atomic Structure (Class 11 notes)
Answer (a): Two bond pairs and no lone pairs on C give a linear shape.
Revise: Chemical Bonding (Class 11 notes)
Answer (a): Chlorine has the highest value; fluorine's small size causes repulsion in its compact shell.
Revise: Classification of Elements (Class 11 notes)
Answer (d): $3x+4(-2)=0$ so $x=+8/3$.
Revise: Oxidation and Reduction (Class 11 notes)
Answer (a): A metal oxide of an alkaline earth metal reacts with acids to form salts.
Revise: Chemistry of Non-Metals (Class 11 notes)
Answer (a): Sodium is obtained by electrolysis of fused NaCl in the Down's cell.
Revise: Chemistry of Metals (Class 11 notes)
Answer (a): A propane chain with two methyl groups on carbon 2.
Revise: Fundamental Principles (Class 11 notes)
Answer (a): $Al_4C_3+12H_2O\to4Al(OH)_3+3CH_4$.
Revise: Hydrocarbons (Class 11 notes)
Answer (c): Proteins are chains of $\alpha$-amino acids joined by peptide bonds.
Revise: Amines (Class 12 notes)
Answer (a): Glucose has a free aldehyde group, a reducing sugar giving Tollens' test.
Revise: Aldehydes and Ketones (Class 12 notes)
Answer (a): DDT kills insects.
Revise: Chemistry in the Service to Mankind (Class 12 notes)
Answer (b): Tranquilizers calm the nervous system in mental stress.
Revise: Chemistry in the Service to Mankind (Class 12 notes)
Answer (a): Each C forms three sigma bonds in a planar ring, so it is $sp^2$.
Revise: Aromatic Hydrocarbons (Class 11 notes)
Answer (c): Victor Meyer's test gives red, blue and no colour for the three classes.
Revise: Alcohols (Class 12 notes)
Answer (a): Zn-Hg with conc. HCl is the Clemmensen reduction.
Revise: Aldehydes and Ketones (Class 12 notes)
Answer (c): In aqueous solution basicity depends on both the +I effect and solvation, and the secondary amine $(CH_3)_2NH$ is the strongest base. The tertiary amine is less solvated and weaker; the gas-phase order would differ.
Revise: Amines (Class 12 notes)
Answer (a): White vitriol is hydrated zinc sulphate.
Revise: Chemistry of Metals (Class 11 notes)
Answer (c): Cinnabar is HgS.
Revise: Chemistry of Metals (Class 11 notes)
Answer (a): $[H^+]=0.04$, $pH=-\log0.04=1.4$.
Revise: Ionic Equilibrium (Class 12 notes)
Answer (c): Cell constant = $l/A$, in $cm^{-1}$.
Revise: Electrochemistry (Class 12 notes)
Answer (c): Rate $=k[A]$, so $k$ has units of $s^{-1}$.
Revise: Chemical Kinetics (Class 12 notes)
Answer (d): Concentration does not depend on the amount of substance.
Revise: Chemical Thermodynamic (Class 12 notes)
Answer (a): The curie is a unit of radioactivity.
Revise: Nuclear Chemistry (Class 12 notes)
Answer (a): This complex is sodium nitroprusside.
Revise: Study of Heavy Metals (Class 12 notes)