Recent questions tagged 2009

The synthesis of crotonaldehyde from acetaldehyde is an example of .................. reaction.

asked Oct 15, 2013 by meena.p

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For the following cell reaction $Ag | Ag^{+} | AgCl | Cl^{\ominus } | Cl_2,Pt\; \Delta G^{\circ}_f (AgCl)=-109\; kJ/mol;$$\Delta G^{\circ}_f (Cl^{\ominus})=-129 \; kJ/mol;\Delta G^{\circ}_f (Ag^+)=78\; kJ/mol ; E^{\circ}$ of the cell is :

asked Oct 15, 2013 by meena.p

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Consider the following reaction

asked Oct 15, 2013 by meena.p

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During the depression of freezing point experiment an equilibrium is established between the molecules of :

asked Oct 15, 2013 by meena.p

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Parkinson's disease is linked to abnormalities in the level of dopamine in the body. The structure of dopamine is :

asked Oct 15, 2013 by meena.p

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A codon has a sequence of $\underline {\underline {A}}$, and specifies a particular $\underline {\underline {B}}$ that is to be incorporated into a $\underline {C}$. What are $\underline {A},\underline {B},\underline {C}?$

asked Oct 15, 2013 by meena.p

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How many tripeptides can be prepared by linking the amino acids glycine, alanine and phenyl alanine?

asked Oct 15, 2013 by meena.p

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What are $\underline {X}$ and $\underline {Y}$ in the following reaction sequence :$C_2H_5OH \longrightarrow \underline{X} \longrightarrow \underline{Y}$

asked Oct 15, 2013 by meena.p

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Which one of the following order is correct for the first ionisation energies of the elements?

asked Oct 15, 2013 by meena.p

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Match the following :

asked Oct 15, 2013 by meena.p

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pH of a buffer solution decreases by $0.02$ units when $0.12 $ g of acetic acid is added to $250\;ml$ of a buffer solution of acetic acid and Potassium acetate at $27^{\circ}$. The buffer capacity of the solution is :

asked Oct 15, 2013 by meena.p

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How many 'ml' of perhydrol is required to produce sufficient oxygen which can be used to completely convert 2 lit of $SO_2$ gas to $SO_3$ gas?

asked Oct 15, 2013 by meena.p

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Assertion (A) : K,Rb and Cs form superoxides. Reason (R): The stability of the superoxides increase from 'K' to 'Cs' due to decrease in lattice energy.

asked Oct 15, 2013 by meena.p

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The average kinetic energy of one molecule of an ideal gas at $27^{\circ}C$ and 1 atm. pressure is :

asked Oct 15, 2013 by meena.p

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Aluminium reacts with $NaOH$ and forms compound 'X'.If the coordination number of aluminium in $'X'$ is 6, the correct formula of X:

asked Oct 15, 2013 by meena.p

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$1.5\;g$ of $CdCl_2$ was found to contain $0.9\;g$ of Cd. Calculate the Atomic weight of $Cd.$

asked Oct 15, 2013 by meena.p

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$SiCl_4$ on hydrolysis forms $'X'$ and HCl. Compound $'X'$ loses water at $1000^{\circ}$ and gives $'Y'$. Compounds $'X'$ and $'Y'$ respectively are :

asked Oct 15, 2013 by meena.p

1 answer

Dipole moment of $HCL=1.03\;D,HI=0.38\;D$. Bond length of $HCL=1.3\; A$ and $HI=1.6 A$. The ratio of fraction of an electric charge, $\delta$, existing on each atom in HCl and HI is :

asked Oct 15, 2013 by meena.p

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Which pair of oxyacids of phosphorous contains $'P-H'$ bonds ?

asked Oct 15, 2013 by meena.p

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In Gattermann reaction, a diazonium group is replaced by $\underline {X}$ using $\underline{Y},X,Y$ are :

asked Oct 15, 2013 by meena.p

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The type of bonds present in sulphuric anhydride :

asked Oct 15, 2013 by meena.p

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The chemical entities present in thermosphere of the atmosphere:

asked Oct 15, 2013 by meena.p

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Electrons with a kinetic energy of $6.023 \times 10^4 \;j/mol$ are evolved from a surface of a metal , when it is exposed to radiation of wavelength of $600\;nm$. The minimum amount of energy required to removed an electron from the metal atom is:

asked Oct 14, 2013 by meena.p

1 answer

Which one of the following sets correctly represent the increase in the paramagnetic property of the ions?

asked Oct 14, 2013 by meena.p

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The wave lengths of electron waves in two orbits is $3:5$ The ratio of kinetic energy of electrons will be :

asked Oct 14, 2013 by meena.p

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The number of $p \pi-d \pi $ 'pi' bonds present in $XeO_3$ and $XeO_4$ molecules, respectively:

asked Oct 14, 2013 by meena.p

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One mole of alkene $\underline {X}$ on ozonolysis gave one mole of acetaldehyde and one mole of acetone. The IUPAC name of $\underline{X}$ is :

asked Oct 14, 2013 by meena.p

1 answer

Fluorine reacts with dilute $NaOH$ and forms a gaseous and forms a gaseous product $\underline{A}$. The bond angle in the molecule of $\underline{A}$ is :

asked Oct 14, 2013 by meena.p

1 answer

Identify the alkyne in the following sequence of reactions:

asked Oct 14, 2013 by meena.p

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Given that $\Delta H_f(H)=218 kJ/mol,$ express the $H-H$ bond energy in Kcal/mol:

asked Oct 14, 2013 by meena.p

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A wheel of radius 0.4 m can rotate freely about its axis as shown in the figure. A string is wrapped over its rim and a mass of 4 kg is hung. An angular acceleration of $8\;rad-s^{-2}$ is produced in it due to the torque. Then moment of inertia of the wheel is :

asked Oct 14, 2013 by meena.p

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A rod of length l is held vertically stationary with its lower and located at a point 'P', on the horizontal plane. When the rod is released to topple about 'P', the velocity of the upper end of the rod with which it hits the ground is :

asked Oct 14, 2013 by meena.p

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Two persons A and B are located in X-Y plane at the points at the points (0,0) and (0,10) respectively. (The distance are measured in MKS units). At a time $t=0$, they start moving simultaneously with velocities $\bar {v}_A=2 \hat j m/s$ and $\bar v_B=2 \hat i m/s$ respectively. The time after which A and B are at their closest distance is :

asked Oct 14, 2013 by meena.p

1 answer

A bullet of mass $0.02\;kg$ travelling horizontally with velocity $250\;ms^{-1}$ strikes a block of wood of mass $0.23\;kg $ which rests on a rough horizontal surface. After the impact, the block and bullet move together and come to rest after travelling a distance of $40\;m$ . The coefficient of sliding friction of the rough surface is : $(g=9/8 ms^{-2})$

asked Oct 14, 2013 by meena.p

1 answer

Currents flowing in each of the following circuits A and B respectively are :

asked Oct 14, 2013 by meena.p

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The radio activity of a sample is $'X'$ at a time $'t_1'$ and $'Y'$ at a time '$t_2'$. If the mean life time of the specimen is 't', the number of atoms that have disintegrated in the time interval $(t_1-t_2)$ is :

asked Oct 14, 2013 by meena.p

1 answer

A photon of energy 'E' ejects a photo electron from a metal surface whose work function is $W_0$. If this electron enters into a uniform magnetic field of induction 'B' in a direction perpendicular to the field and describes a circular path of radius 'R' , then the radius 'r' is given by , (in the usual notation):

asked Oct 14, 2013 by meena.p

2 answers

The work function of a certain metal is $3.31 \times 10^{-19}\;J$. Then the maximum kinetic energy of photo electrons emitted by radiation of wavelength 5000 A is : (given $h=6.62 \times 10^{-34}\;J-s, C= 3 \times 10^{8}ms^{-1},e= 1.6 \times 10^{-19}$ coul.)

asked Oct 14, 2013 by meena.p

1 answer

An infinitely long straight conductor is bent into the shape as shown below. It carries a current of i Amps, and the circular loop is R meters. Then the magnitude of magnetic induction at the center of the circular loop is :

asked Oct 14, 2013 by meena.p

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A wire of length 'l' is bent into a circular loop of radius R and carries a current I. The magnetic field at the center of the loop is 'B'. The same wire is now bent into a double loop of equal radii. If both loops carry the same current I and it is in the same direction, the magnetic field at the center of the double loop will be :

asked Oct 14, 2013 by meena.p

1 answer

The following series $L-C-R$ circuit, when driven by an e.m.f source of angular frequency 70 Kilo-radius per second, the circuit effectively behaves like :

asked Oct 14, 2013 by meena.p

1 answer

A cell in secondary circuit gives null deflection for $2.5\;m$ length of potentiometer having 10 m length of wire. If the length of the potentiometer wire is increased by 1 m without changing the cell in the primary, the position of the null point now is :

asked Oct 14, 2013 by meena.p

1 answer

In the circuit shown below, a voltmeter of internal resistance R, When connected across B and C reads $\large\frac{100}{3}$ volts. Neglecting the internal resistance of the battery, the value of R is :

asked Oct 14, 2013 by meena.p

1 answer

Two point charges $-q$ and $+q$ are located at points $(0,0,-a)$ and $(0,0,a)$ respectively.The electric potential at a point $(0,0,z)$ where $ z > a$ is :

asked Oct 14, 2013 by meena.p

1 answer

An infinitely long thin straight wire has uniform linear charge density of $ \large\frac{1}{3}\;$$ coul.m^{-1}. $ Then the magnitude of the electric intensity at a point 18 cm away is : (given $\in _{0}=8.8 \times 10^{-12} C^2 /N-m^2)$

asked Oct 14, 2013 by meena.p

1 answer

A bar magnet of 10 cm long is kept with its north (N)-pole pointing North. A neutral point is formed at a distance of 15 cm from each pole. Given the horizontal component of earth's field is $0.4$ Gauss, the pole strength of the magnet is :

asked Oct 11, 2013 by meena.p

1 answer

Two bar magnets A,B are placed one over the other and are allowed to vibrate in a vibration magnetometer. They make 20 oscillations per minute when the similar poles of A and B are on the same side, While they make 15 oscillations per minute when their opposite poles lie on the same side. If $M_A$ and $M_B$ are the magnetic moments of A and B and if $M_A > M_B$, the ratio of $M_A$ and $M_B$ is :

asked Oct 11, 2013 by meena.p

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The two lenses of an achromatic doublet should have :

asked Oct 11, 2013 by meena.p

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Four light sources produce the following four waves :(i) $y_1= a \sin(\omega t+\phi _1)$ (ii) $y_2= a \sin 2 \omega t $ (iii) $y_3= a' \sin(\omega t+\phi _2)$ (iv) $y_4= a' \sin(3 \omega t+\phi)$ Superposition of which two waves give rise to interference ?

asked Oct 11, 2013 by meena.p

1 answer

In Young's double slit experiment, the 10th maximum. When the wavelength $\lambda _1$ is at a distance of $y_1$ from the central maximum. When the wavelength of the source is changed to $\lambda_2,5$ th maximum is at a distance of $y_2$ from its central maximum. The ratio $\bigg(\large\frac{y_1}{y_2}\bigg)$is :

asked Oct 11, 2013 by meena.p

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