Recent questions in JEEMAIN-2015

Which one has the highest boiling point ?

asked Nov 4, 2015 by meena.p

1 answer

Match the catalysts

asked Nov 4, 2015 by meena.p

0 answers

Match the catalysts

asked Nov 4, 2015 by meena.p

1 answer

Higher order (<3) reactions are due to :

asked Nov 4, 2015 by meena.p

1 answer

From the following statements regarding $H_2O_2$ , choose the incorrect statement :

asked Nov 4, 2015 by meena.p

1 answer

The ionic radii (in A) of $N^{3-},O^{2-}$ and $F^{-}$ are respectively :

asked Nov 4, 2015 by meena.p

1 answer

Which of the following compounds will exhibit geometrical isomerism?

asked Nov 4, 2015 by meena.p

1 answer

In the context of the Hall- Heroult process for the extraction of $Al$ which of the following statement is false ?

asked Nov 4, 2015 by meena.p

1 answer

The inter molecular interaction that is dependent on the inverse cube of distance between the molecules is :

asked Nov 4, 2015 by meena.p

1 answer

The synthesis of alkyl fluorides is best accomplished by :

asked Nov 4, 2015 by meena.p

1 answer

The number of geometric isomers that can exists for square planar $[Pt(Cl)(py)(NH_3)(NH_2OH)]^+$ is (py=pyridine )

asked Nov 4, 2015 by meena.p

1 answer

Which one of the following alkaline earth metal sulphates has its hydration enthalpy greater than its lattice enthalpy ?

asked Nov 4, 2015 by meena.p

1 answer

The following reaction is performed at $298\;K$ $2NO(g) +O_2(g) \to 2NO_2(g)$ . The standard free energy of formation of $NO(g)$ is $86.6\;kJ\; mol$ at $298\;K$ . What is the standard free energy of formation of $NO_2 (g)$ at $298\;K\; (K_p = 1.6 \times 10^{12})$

asked Nov 4, 2015 by meena.p

1 answer

Assertion : Nitrogen and Oxygen are the main component in the atmosphere but these but these do not react to form oxides of nitrogen . Reason : The reaction between nitrogen and Oxygen requires high temperature .

asked Nov 4, 2015 by meena.p

1 answer

In Carius method of estimation of halogens, $250\;mg$ of an organic compound gave $141\;mg$ of $AgBr$ . The percentage of bromine in the compound is

asked Nov 4, 2015 by meena.p

1 answer

The molecular formula of a commercial resin used for exchanging ions in water softening is $C_8H_7SO_3Na$ (Mol.wt.206) What would be the maximum uptake of $Ca^{2+}$ ions by the resin when expressed in mole per gram resin ?

asked Nov 4, 2015 by meena.p

1 answer

Which polymer is used in the manufacture of paints and lacquers ?

asked Nov 4, 2015 by meena.p

1 answer

Which among the following is the most reactive ?

asked Nov 4, 2015 by meena.p

1 answer

Which of the following is the energy of a possible excited state of hydrogen ?

asked Nov 4, 2015 by meena.p

1 answer

3g of activated charcoal was added to 50 mL of acetic acid solution $(0.06\;N)$ in a flask. After an hour it was filtered was found to be $0.042\;N$ . The amount of acetic acid absorbed (per gram of charcoal ) is :

asked Nov 3, 2015 by meena.p

1 answer

The Vapour pressure of acetone at $20^{\circ}C$ is $185\;torr$ .When $1.2 \;g$ of a non- volatile substance was dissolved in 100 g of acetone at $20^{\circ}$ its vapour pressure was $183$ torr. The molar mass $(g mol^{-1}) of the substance is :

asked Nov 3, 2015 by meena.p

1 answer

When 5V potential difference is applied across a wire of length $0.1\;m$ , the drift speed of electrons is $2.5 \times 10^{-4}\;ms^{-1}$ . If the electron density in the wire is 48 \times 10^{-3}$, the resistivity of the material is close to :

asked Nov 3, 2015 by meena.p

1 answer

From a solid sphere of mass M and radius R a cube of maximum possible volume is cut. Moment of inertia of cube about an axis passing through its center and perpendicular to one of its faces is :

asked Nov 3, 2015 by meena.p

1 answer

A pendulum made of a uniform wire of cross sectional area A has time period T.When an addition mass M is added to its bob, the time period change to $T_M$ . If the young's modulus of material of the wire is Y then $\large\frac{1}{Y}$ is equal to:

asked Nov 3, 2015 by meena.p

1 answer

Two coaxial solenoids of different radii carry current I in the same direction. Let $\overrightarrow{F_1}$ be the magnetic force on the inner solenoid due to the outer one and $\overrightarrow{F_2}$ be the magnetic force on the outer solenoid due to the inner one . Then :

asked Nov 3, 2015 by meena.p

1 answer

A signal of $5kHz$ frequency is amplitude modulated on a carrier wave of frequency $2\;MHz$ . The frequency of the resultant signal is/are :

asked Nov 3, 2015 by meena.p

1 answer

Assuming human pupil to have a radius of $0.25\;cm$ and a comfortable viewing distance of $25\;cm$ , the minimum seperation between two objects that human eye can resolve at 500 nm wavelength is :

asked Nov 3, 2015 by meena.p

1 answer

A long cylindrical shell carries positive surface charge $\sigma$ in the upper half and negative surface charge $-\sigma$ in the lower half. The electric field lines around the cylinder will look like figure given in : (figure are schematic and not drawn to scale )

asked Nov 3, 2015 by meena.p

1 answer

A uniformly charged solid sphere of radius R has potential $V_0$ (measured with respect to $\infty$ ) on its surface. For this sphere the equipotential surfaces with potentials $\large\frac{3V_0}{2},\frac{5V_0}{4},\frac{3V_0}{4}$ and $\large\frac{V_0}{4}$ have radius $R_1, R_2, R_3$ and $R_4$ respectively . Then

asked Nov 3, 2015 by meena.p

1 answer

An inductor $(L=0.03H)$ and a resistor $(R= 0.15\;k\Omega)$ are connected in series to battery of $15\;V\;EMF$ in a circuit shown below. The key $K_1$ has been kept closed below. . The key kept closed for a long time. Then at $t=0$ , $K_1$ is opened and the key $K_2$ is closed simultaneously . At $t= 1\;ms$ , the current in the circuit will be : $(e^5 \approx 150)$

asked Nov 3, 2015 by meena.p

1 answer

A solid body of constant heat capacity $1 L/^{\circ}C$ is being heated by keeping it in contact with reservoirs in two ways : (i) Sequentially keeping in contact with 2 reservoirs such that each reservoir supplies same amount of heat . (ii) Sequentially keeping in contact with 8 reservoirs such that each reservoir supplies same amount of heat . In both the cases body is brought from initial temperature $100^{\circ}$ to final temperaure $200 ^{\circ}$ Entropy change of the body in the two cases respectively is :

asked Nov 3, 2015 by meena.p

1 answer

An LCR circuit is equivalent to a damped pendulum. In an LCR circuit the capacitor is charged to $Q_0$ and then connected to the L and R as shown below : If a student plots graphs of the square of maximum charge $(Q^2_{max})$ on the capacitor with time(t) for two different values $L_1$ and $L_2(L_1 > L_2)$ of L then which of the following represents this graph correctly ?

asked Nov 3, 2015 by meena.p

1 answer

A train is moving on a straight track with speed $20ms^{-1}$ . It is blowing its Whistle at the frequency of 1000 Hz. The percentage change in the frequency heard by a person standing near the track as the train passes him is (speed of sound = $320\;ms^{-1})$ close to :

asked Nov 3, 2015 by meena.p

1 answer

For a simple pendulum , a graph is plotted between its kinetic energy (KE) and potential energy(PE) against its displacement d. which one of the following represents these correctly ?

asked Nov 3, 2015 by meena.p

1 answer

Two stones are thrown up simultaneously from the edge of a cliff $240\;m$ high with initial speed of $10 m/s$ and $40 m/s$ respectively. Which of the following graph best represents the time variation of relative position of the second stone with respect to the first ? (Assume stones do not rebound after hitting the ground and neglect air resistance , take $g= 10 m/s^2$ ) (The figures are schematic and not drawn to scale )

asked Nov 3, 2015 by meena.p

1 answer

Monochromatic light is incident on a glass prism of angle A. If the refractive index of the material of the prism is $\mu$ , a ray, incident at an angle $\theta$ , on the face $AC$ of the prism provided:

asked Nov 3, 2015 by meena.p

1 answer

From a solid sphere of mass M and radius R, a spherical portion of radius $\large\frac{R}{2}$ is removed , as shown in fig. Taking gravitational potential $V=0$ at $r= \infty$ , the potential at the center of the cavity thus formed is:

asked Nov 3, 2015 by meena.p

1 answer

On a hot summer night, the refractive index of air is smallest near the ground and increases with height from the ground . When a light beam is directed horizontally, the Huygen's principle leads us to conclude that as it travels , the light beam:

asked Nov 3, 2015 by meena.p

1 answer

As an electron makes a transition from an excited state to the ground state of a hydrogen - like atom /ion:

asked Nov 3, 2015 by meena.p

1 answer

Consider a spherical shell of radius R at temperature T. The black body radiation inside it can be consider as an ideal gas of photons with internal energy per unit volume $u= \large\frac{U}{V}$ $\alpha T^4$ and pressure $P= \large\frac{1}{3} \bigg( \frac{U}{V} \bigg)$ . If the shell now undergoes an adiabatic expansion the relation between T and R is :

asked Nov 3, 2015 by meena.p

1 answer

A rectangular loop of sides 10 cm and 5 cm carrying a current I of 12 A is placed in different orientations as shown in the figure below : If there is a uniform magnetic field of $0.3\;T$ in the positive z direction , in which orientation the loop would be in (i) stable equilibrium and (ii) unstable equilibrium ?

asked Nov 3, 2015 by meena.p

1 answer

Consider an ideal gas confined in an isolated closed chamber . As the gas undergoes an adiabatic expansion , the average time of collision between molecules increases as $V^{q}$ , Where V is the volume of the gas . The value of q is : $\bigg(\gamma = \large\frac{C_p}{C_v}\bigg)$

asked Nov 3, 2015 by meena.p

1 answer

Given in the figure are two blocks A and NB of weight $20\;N$ and $100\;N$ respectively . These are being pressed against a wall by a force F as shown. If the coefficient of friction between the blocks uis $0.1$ and between block B and the wall is $0.15$ , the frictional force applied by the wall on block B is :

asked Nov 3, 2015 by meena.p

1 answer

A particle of mass m moving in the x direction with speed 2v is hit by another particle of mass 2m moving in the y direction with speed v. If the collision is perfectly inelastic , the percentage loss in the energy during the collision is close to:

asked Nov 3, 2015 by meena.p

1 answer

Two long current carrying thin wires, both with current I, are held by insulating threads of length L and are in equilibrium as shown in the figure, with threads making an angle $\theta$ with the vertical. If wires have mass $\lambda$ per unit length then the value of I is : (g= gravitational acceleration )

asked Nov 3, 2015 by meena.p

1 answer

In the given circuit, charge $Q_2$ on the $2 \mu F$ capacitor changes as C is varied from $1 \mu F$ to $3 \mu F$ . $Q_2$ as a function of $'C'$ is given properly by :

asked Nov 3, 2015 by meena.p

1 answer

A red LED emits light at $0.1$ watt uniformly around it. The amplitude of the electric field of the light at a distance of $1\;m$ from the diode is :

asked Nov 2, 2015 by meena.p

1 answer

The period of oscillation of a simple pendulum is $T= 2 \pi \sqrt {\large\frac{L}{g}}$ . Measured value of L is $20.0\;cm$ known to 1mm accuracy and time for 100 oscillations of the pendulum is found to be 90 s using a wrist watch of 1 s resolution . The accuracy in the determination of g is :

asked Nov 2, 2015 by meena.p

1 answer

Match List I (Fundamental experiement ) with List II (its conclusion ) and select the correct option from the choices given below list :

asked Nov 2, 2015 by meena.p

1 answer

Distance of the center of mass of a solid uniform cone from its vertex is $z_0$ . If the radius of its base is R and its height is h then $z_0$ is equal to :

asked Nov 2, 2015 by meena.p

1 answer

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