Recent questions tagged past papers

Aceic acid is reacted with metallic sodium to form hyrdogen and X. When X is heated with sodalime, Y and sodium carbonate are formed. Y is ......... ?

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When acetaldehyde is reacted with $LiAlH_4$, whar is the product formed ?

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Dry distillation of calcium acetate and calcium formate forms :

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What is $Y$ in the following reaction ? $C_2H_5I + NaOC_2H_5 \to X + NaI$ $X + 2HI \xrightarrow{\Delta} 2Y + H_2O$

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Absolute alcohol (100% alcohol) is prepared by distilled rectified spirit over :

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3 moles of ethanol reacts with one mole of phosphorus tribromide to form 3 moles of bromo-ethane and one mole of X. Which of the following is X ?

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Chloroethane reacts with $X$ to form diethyl ether. What is $X$ ?

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Ethanol, when reacted with $PCl_5$ gave $A$, $POCl_3$ and $HCl$. A reacts with silver nitrate to form $B$ ( major product) and $AgCl$. $A$ and $B$ are respectively :

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Which one of the following is used in the preparation of styrene ?

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Consider the following reactions $C_2H_2 \xrightarrow[\text{500$^{\circ}$C}]{\text{red hot iron tube}} A$ $A \xrightarrow[\text{70$^{\circ}$C}]{\text{conc. $HNO_3$, conc. $H_2SO_4$}} B$ $B \xrightarrow{LiAlH_4} C_6H_5 - N = N - C_6H_5$ A and B are :

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Which one of the following pairs of compounds are functional isomers ?

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The structural formula 2-methyl-2-butene is :

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Which one of the following is mainly responsible for depletion of ozone layer ?

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Which one of the following ions exhibits highest magnetic moment ?

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The number of Ione pairs of electrons present on $Xe$ in $XeF_4$ is :

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Which one of the following halogen liberated oxygen, when passed through hot concentrated KOH solution ?

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Which one of the following order is correct for the bond energies of halogen molecules ?

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What are the products formed when chlorine is passed through aqueous hypo solution ?

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What are the products obtained when ammonia is reacted with excess chlorine ?

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Ionic radius (in $\mathring{A}$) of $As^{3+}, \; Sb^{3+}$ and $Bi^{3+}$ follow the order :

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The catenation tendency of $C, Si $ and $Ge$ is in the order $Ge < Si < C$. The bond energies (in $kJ\; mol^{-1}$) of $C-C, \; Si-Si$ and $Ge-Ge$ bonds, respectively are :

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What is the molecular formula of borazole ?

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During the electrolytic reduction of alumina, the reaction at cathode is :

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In organic reactions, sodium in liquid ammonia is used as :

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The electronic configuration of elements A, B and C are $[He]2s^1, [Ne] 3s^1 $ and $[Ar] 4s^1$ respectively, which one of the following order is correct for the first ionization potentials (in $k.J.\; mol^{-1}$) of A, B and C ?

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......... process is used for the removal of hardness of water :

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In which of the following reactions, $H_2O_2$ acts as a reducing reagents ?

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Which one of the following reactions is an example of heterogeneous cataysis ?

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A steel meter scale is to be ruled so hat millimeter intervals are accurate within about $5 \times 10^{-5}m$ at a certain temperature. The maximum temperature variation allowable during the ruling is: (Coefficient of linear expansion of steel = $10 \times 10^{-6} K^{-1}$)

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A tank with vertical walls is mounted so that its base is at a height $H$ above the horizontal ground. The tank is filled with wate to a depth $'h'$. A hole is punched in the side wall of the tank at a depth $'x'$ below the water surface. To have maximum range of the emerging stream, the value of $x$ is :

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Water is conveyed through a uniform tube of 8 cm in diameter and 3140 m in length at the rate $2 \times 10^{-3} m^3$ per second. The pressure required in maintain the flow is : (Viscosity of water = $10^{-3}$ SI units )

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A mercury drop of radius 1 cm is sprayed into $10^6$ drop of equal size. The energy expanded in joules is : (Surface tension of mercury is $460 \times 10^{-3} N/m$)

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The length of an elastic string is $'a'$ metres when the longitudinal tension is 4 N and $'b'$ meters when the longitudinal tension is 5 N. The length of the string in metres when the longitudinal tension is 9 N is :

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A body is executing simple harmonic motion. At a displacement $x$ its potential energy is $E_1$ and at a displacement $y$ its potential energy is $E_2$. The potenital energy $(E)$ at displacement $(x+y)$ is :

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Two particles P and Q start from origin and execute simple harmonic motion along X-axis with the same amplitude but with period 3 seconds and 6 seconds respectively. The ratio of the velocities of P and Q when they meet is :

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Mass $M$ is divided into two parts $''xm''$ and $''(1-x)m''$. For a given separation the value of $x$ for which the gravitational attraction between the two pieces becomes maximum is :

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From a uniform wire, two circular loops are made (i) $P$ of radius $'r'$ and (ii) $Q$ of radius $nr$. If the moment of inertia of $Q$about an axis passing through its centre and perpendicular to its plane is 8 times that of $P$ about a similar axis, the value of $'n$ is (diameter of the wire is very much smaller than $i$ or $nr$ ) :

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A uniform metal rod of length 'L' and mass 'M' is rotating about an axis passing through one of the ends & perpendicular to the rod with angular speed $'\omega'$. If the temperature increases by $t^{\circ}C$, then the change in its angular velocity is proportional to which of the following ? (Coefficient of linear expansion of rod = $\alpha$)

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A particle is projected up along a rough inclined plane of inclination $45^{\circ}$ with the horizontal. If the coefficient of friction is $0.5$, the acceleration is : (g = Acceleration due to gravity)

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A body of weight $''64 N''$ is pushed with just enough force to start it moving across a horizontal floor and the same force continues to act afterwards. If the coefficients of static and dynamic friction are 0.6 and 0.4 respectively, the acceleration of the body is : (acceleration due to gravity = g)

asked Dec 11, 2018 by pady_1

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The velocities of three particles of masses $20\; g, \; 30\; g$ and $50\; g$ are $10 \hat{i}, \; 10 \hat{j}$ and $10 \hat{k}$ respectively. The velocity of the centre of mass of the three particles is :

asked Dec 11, 2018 by pady_1

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A force applied by an engine on a train of mass $2.05 \times 10^6 kg$ changes its velocity from $5 \; m/s$ to $25\; m/s$ in 5 minutes. The power of the engine is :

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A body of mass $6 \;kg$ is under a force which causes displacement in it given by $'' s = \frac{t^2}{4}''$ metres where $'t'$ is time. The work done by the force in 2 seconds is :

asked Dec 11, 2018 by pady_1

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An object is projeced with a velocity of $20\;m/s$ making an angle of $45^{\circ}$ with horizontal. The equation for the trajectory is $"h = Ax - Bx^2"$ where $'h'$ is height, $'x'$ is horizontal distance A and B are constats. The ratio $A : B$ is : $(g = 10\;m/s^2)$

asked Dec 11, 2018 by pady_1

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A particle falls from a height 'h' upon a fixed horizontal plane and rebounds. If 'e' is the coefficient of restitution, the total distance travelled before rebound-ing has stopped is :

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An electron moes with speed $2 \times 10^5\; m/s$ along the positive $x$-direction in the presence of a magnetic field of induction $\overrightarrow{B} = \hat{i} + 4 \hat{j} - 3 \hat{k}$ (in tesla). The magnitude of the force experienced by the electron in newtons is : (Charge on the electron =$1.6 \times 10^{-19}C$)

asked Dec 11, 2018 by pady_1

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In an experiment of simple pendulum, the errors in the measurement of length of the pendulum (L) and time period (T) are 3% and 2% respectively. The maximum percentage error in the value of $\frac{L}{T^2}$ is :

asked Dec 11, 2018 by pady_1

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In CGS system magnitude of the force is 100 dynes . In another system where the fundamental physical quantities are kilogram, meter and minute, the magnitude of the force is :

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While a collector to emitter voltage is constant in a transistor, the collector current enhanges by $8.2\;mA$ when the emitter current changes by $8.3\;mA$. The value of forward current ratio is :

asked Dec 11, 2018 by pady_1

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A heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio $3:1$. The ratio of radii of the fragments is :

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