Recent questions tagged 2015

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 12, 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 12, 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 separation between two objects that human eye can resolve at 500 nm wavelength is :

asked Nov 12, 2015 by meena.p

1 answer

In the circuit shown,the current in the $1 \Omega$ resistor is :

asked Nov 5, 2015 by meena.p

1 answer

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

asked Nov 5, 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 density in the wire is $8 \times 10^{28}\;m^{-3}$, the resistivity of the material is close to :

asked Nov 5, 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 5, 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 5, 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 5, 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 $1m$ from the diode is

asked Nov 5, 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 5, 2015 by meena.p

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Two Faraday of electricity is passed through a solution of $CuSO_4$ . The mass of copper deposited at the cathode is : (at . mass of Cu=63.5 amu)

asked Nov 5, 2015 by meena.p

1 answer

The color of $kMnO_4$ is due to

asked Nov 5, 2015 by meena.p

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Which of the vitamins given below is water soluble ?

asked Nov 5, 2015 by meena.p

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In the following sequence

asked Nov 5, 2015 by meena.p

1 answer

Which of the following compounds

asked Nov 5, 2015 by meena.p

1 answer

Which compound would give 5 -keto-2-methyl hexanal upon ozonolysis ?

asked Nov 4, 2015 by meena.p

1 answer

The standard Gibbs energy changes at 300 k for the reaction $2A= B+C$ is $2494.2\;J$ At a given time, the composition of the reaction mixture is $[A]=\large\frac{1}{2}$$,[B] =24$ and $[C]=\frac{1}{2} $. The reaction proceeds in the : $[R= 8.314\;J/K/mol,e = 2.718]$

asked Nov 4, 2015 by meena.p

1 answer

Sodium metal crystallizes in a body centered cubic lattice with a unit cell edge of $44.29 \dot{A}$ the radius of sodium atom is approximately :

asked Nov 4, 2015 by meena.p

1 answer

Which of the following compounds is not colored yellow ?

asked Nov 4, 2015 by meena.p

1 answer

In the reaction

asked Nov 4, 2015 by meena.p

1 answer

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

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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

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