Recent questions tagged 2018

Consider the following species : $CN^+, CN^-, NO$ and $CN$ Which one of these will have the highest bond order ?

asked Aug 21, 2018 by pady_1

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Which one is a wrong statement ?

asked Aug 21, 2018 by pady_1

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Iron exhibits bcc structure at room temperature. About $900^oC$, it transforms to fcc structure. The ratio of density of iron at room temperature to that at $900^oC$ (assuming molar mass and atomic radii of iron remains constant with temperature) is

asked Aug 21, 2018 by pady_1

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Magnesium reacts with an element (X) to form an ionic compoun. If the ground state electronic configuration of (X) is $1s^2 2s^2 2p^3$, the simplest formula for this compound is

asked Aug 21, 2018 by pady_1

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Which of the followng carbocations is expected to be most stable ?

asked Aug 21, 2018 by pady_1

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Which of the following molecules represents the order of hybridisation $sp^2, sp^2, sp, sp$ from left to right atoms?

asked Aug 21, 2018 by pady_1

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Which of the following is correct with reapect to -I effect of the substituents ? (R = alkyl)

asked Aug 21, 2018 by pady_1

0 answers

The correct difference between first and second order reactions is that

asked Aug 21, 2018 by pady_1

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In which case in number of molecules of water maximum ?

asked Aug 21, 2018 by pady_1

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Among $CaH_2, BeH_2, BaH_2$, the order of ionic character is

asked Aug 21, 2018 by pady_1

1 answer

Consider the change in oxidation state of Bromine corresponding to different emf values as shown in the diagram below : $BrO_4^- \xrightarrow{1.82 V} BrO_3^- \xrightarrow{1.5 V} HBrO \xrightarrow{1.595 V} Br_2 \xrightarrow{1.0652 V} Br^-$ Then the species undergoing disproportionation is

asked Aug 21, 2018 by pady_1

1 answer

Which one of the following conditions will favour maximum formation of the product in the reaction, $A_2 (g) + B_2 (g) \rightleftharpoons X_2 (g) \Delta_f H = - X\;kJ$ ?

asked Aug 21, 2018 by pady_1

2 answers

For the redox reaction $MnO_4^- + C_2O_4^{2-} + H^+ \to Mn^{2+} + CO_2 + H_2O$ The correct coefficients of the reactants for the balanced equation are

asked Aug 21, 2018 by pady_1

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The correction factor 'a' to the ideal gas equation corresponds to

asked Aug 21, 2018 by pady_1

2 answers

When initial concentration of the reactant is doubled, the half-life period of a zero order reaction

asked Aug 21, 2018 by pady_1

2 answers

The bond dissociation energies of $X_2, Y_2$ and $XY$ are in the ratio of 1 : 0.5 : 1. $\Delta H$ for the formation of $XY$ is $-200\; kJ \;mol^{-1}$. The bond dissociation energy of $X_2$ will be :

asked Aug 21, 2018 by pady_1

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Which oxide of nitrogen is not a common pollutant introduced into the atmosphere both due to natural and human activity?

asked Aug 21, 2018 by pady_1

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The compound $C_7H_8$ undergoes the following reactions: $C_7H_8 \xrightarrow{3Cl_2/ \Delta} A \xrightarrow{Br_2/Fe} B \xrightarrow{Zn/ HCl} C$ The product 'C' is

asked Aug 21, 2018 by pady_1

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Hydrocarbon (A) reacts with bromine by substitution to form an alkyl bromide which by Wurtz reaction is converted to gaseous hydrocarbon containing less than four carbon atoms. (A) is

asked Aug 21, 2018 by pady_1

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The compound A on treatment with Na gives B, and with $PCl_4$ gives C, B and C react together to give diethyl ether. A, B and C are in the order

asked Aug 21, 2018 by pady_1

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Nitrogen of aniline in strong acidic medium also gives m-nitroaniline because

asked Aug 21, 2018 by pady_1

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Regarding cross-linked or network polymers, which of the following statements is incorrect ?

asked Aug 21, 2018 by pady_1

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A mixture of 2.3 g formic acid and 4.5 g oxalic acid is treated with conc. $H_2SO_4$. The evolved gaseous mixture is passed through KOH pellets. Weight (in g) of the remaining product at STP wil be

asked Aug 21, 2018 by pady_1

1 answer

The diffrence between amylose and amylopectin is

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Which of the following oxides is most acidic in nature ?

asked Aug 21, 2018 by pady_1

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When the light of frequency $2v_o$ (where $v_0$ is threshold frequency), is incident on a metal plate, the maximum velocity of electrons emitted is $v_1$. When the frequency of the incident radiation is increased to $5v_0$, the maximum velocity of eletrons emitted from the same plate is $v_2$. The ratio of $v_1$ to $v_2$ is

asked Aug 21, 2018 by pady_1

1 answer

The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom, is

asked Aug 21, 2018 by pady_1

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For a radioactive material, half-life is 10 minutes. If initially there are 600 number of nuclei, the time taken (in minutes) for the disintegration of 450 nuclei is

asked Aug 21, 2018 by pady_1

1 answer

An electron of mass m with an initial velocity $\overrightarrow{V} = V_0 \hat{i} (V_0 > 0) $ enters an electric field $\overrightarrow{E} = -E_0 \hat{i} (E_0 = constant > 0)$ at $t = 0$. If $\lambda_0$ is its de-Broglie wavelength initially, then its de-Broglie wavelength at time t is :

asked Aug 21, 2018 by pady_1

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A small sphere of radius 'r' falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to

asked Aug 21, 2018 by pady_1

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The power radiated by a black body is P and it radiates maximum energy at wavelength, $\lambda_0$. If the temperature of the black body is now changed so that it radiates maximum energy at wavelength $\frac{3}{4} \lambda_D$, the power radiated by it becomes nP. The value of n is

asked Aug 21, 2018 by pady_1

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A sample of 0.1 g of water at $100^oC$ and normal pressure ($1.013 \times 10^5 Nm^{-2}$) requires 54 cal of heat energy to convert to steam at $100^oC$. If the volumn of the steam produced is 167.1 cc, the change in internal energy of the sample, is

asked Aug 21, 2018 by pady_1

1 answer

Two wires are made of the same material and have the same volume. The first wire has cross-sectional area A and the second wire has cross-sectional area 3A. If the length of the first wire is increased by $\Delta x$ on applying a force F, how much forcce is needed to stretch the second wire by the same amount ?

asked Aug 21, 2018 by pady_1

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A body initially at rest and sliding along a frictionless track from a height h (as shown in the figure) just completes a vertical circle of diameter AB = D. The height h is equal to

asked Aug 21, 2018 by pady_1

1 answer

A moving block having mass m, collides with another stationary block having mass 4m. The lighter block comes to rest after collision. When the initial velocity of the lighter block is v, then the value of coefficient of restitution (e) will be

asked Aug 21, 2018 by pady_1

2 answers

Three objects, A : (a solid sphere), B : (a thin circular disk) and C : (a circular ring), each have the same mass M and radius R. They all spin with the same angular speed $\omega$ about their own symmetry axes. The amounts of work (W) required to bring them to rest, would satisfy the relation

asked Aug 21, 2018 by pady_1

1 answer

Which one of the following statements is incorrect ?

asked Aug 21, 2018 by pady_1

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A student measured the diameter of a small steel ball using a screw gauge of least count 0.001 cm. The main scale reading is 5 mm and zero of circular scale division coincides with 25 divisions above the reference level. If screw gauge has a zero error of -0.004 cm, the correct diameter of the ball is

asked Aug 21, 2018 by pady_1

1 answer

The moment of the force, $\overrightarrow{F} = 4 \hat{i} + 5 \hat{j} - 6 \hat{k}$ at (2, 0, -3) about the point (2, -2, -2), is given by

asked Aug 21, 2018 by pady_1

1 answer

A block of mass m is placed on a smooth inclined wedge ABC of inclination $\theta$ as shown in the figure. The wedge is given as acceleration 'a' towards the right. The relation between a and $\theta$ for the block to remain stationary on the wedge is

asked Aug 21, 2018 by pady_1

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A toy car with charge q moves on a frictionless horizontal plane surface under the influence of a uniform electric field $\overrightarrow{E}$. Due to the force q $\overrightarrow{E}$, its velocity increases from 0 to 6 m/s in one second duration. At that instant the direction of the field is reversed. The car continues to move for two more seconds under the influence of this field. The average velocity and the average speed of the toy car between 0 to 3 seconds are respectively

asked Aug 21, 2018 by pady_1

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If the mass of the Sun were ten times smaller and the universal gravitational constant were ten times larger in magnitude, which of the following is not correct ?

asked Aug 21, 2018 by pady_1

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A solid sphere is rotating freely about its symmetry axis in free space. The radius of the sphere is increased keeping its mass same. Which of the following physical quantities would remain constant for the sphere?

asked Aug 21, 2018 by pady_1

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A solid sphere is in rolling motion. In rolling motion a body possesses translational kinetic energy $(K_t)$ as well as rotational kinetic energy $(K_r)$ simultaneously. The ratio $K_t : (K_t + K_r)$ for the sphere is :

asked Aug 21, 2018 by pady_1

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The kinetic energies of a planet in an elliptical orbit about the Sun, at position A, B and C are $K_A, K_B$ aand $K_C$, respectively. AC is the major axis and SB is perpendicular to AC at the position of the Sun S as shown in the figure. Then

asked Aug 21, 2018 by pady_1

1 answer

An electron falls from rest through a vertical distance h in a uniform and vertically upward directed electric field E. The direction of electric field is now reversed, keeping its magnitude the same. A proton is allowed to fall from rest in it through the same vertical distance h. The time of fall of the electron, in comparison to the time of fall of the proton is

asked Aug 21, 2018 by pady_1

1 answer

The electrostatic force between the metal plates of an isolated parallel plate capacitor C having a charge Q and area A, is

asked Aug 21, 2018 by pady_1

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A pendulum is hung from the roof of a sufficiently high building and is moving freely to and fro like a simple harmonic oscillator. The acceleration of the bob of the pendulum is $20 \; m/s^2$ at a distance of 5 m from the mean position. The time period of oscillation is :

asked Aug 21, 2018 by pady_1

2 answers

A tuning fork is used to produce resonance in glass tube. The length of the air column in this tube can be adjusted by a variable piston. At room temperture of $27^oC$ two successive resonances are produced at 20 cm and 73 cm of column length. If the frequency of the tuning fork is 320 Hz, the velocity of sound in air at $27^oC$ is

asked Aug 21, 2018 by pady_1

1 answer

An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of

asked Aug 21, 2018 by pady_1

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