Recent questions tagged 2015

If $2+3i$ is one of the roots of the equation $2x^3-9x2+kx-13=0,$ k \in R$, then the real root of this equation

asked Sep 29, 2015 by meena.p

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The largest value of r for which the region represented by the set $\{\omega \in C/| \omega -4-i| \geq r \}$ is contained in the region represented by the set $\{z \in C/|Z-1| \geq | z+i| \}$ is equal to :

asked Sep 29, 2015 by meena.p

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In a certain town, $25\%$ of the families own a phone and $15 \%$ own a car ; $65\%$ families own neither a phone nor a car and $2,000$ families own both a car and a phone.Consider the following three statements : (a) $5\%$ families own both a car and a phone. (b) $35\%$ families own either a car or a phone. (c) $40,000$ families live in the town. Then,

asked Sep 29, 2015 by meena.p

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The cation that will not be precipitated by $H_2S$ in the presence of dil $HCl$ is :

asked Sep 29, 2015 by meena.p

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Refer the following diagram :

asked Sep 29, 2015 by meena.p

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Match the polymers in column-A with their main uses in column-B and choose the correct answer :

asked Sep 29, 2015 by meena.p

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Arrange the following amines in the order of increasing basicity.

asked Sep 29, 2015 by meena.p

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In the presence of a small amount of phosphorous, aliphatic carboxylic acids react with chlorine or bromine to yield a compound in which a - hydrogen has been replaced by halogen. This reaction is known as :

asked Sep 29, 2015 by meena.p

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A compound A with molecular formula $C_{10}H_{13}Cl$ gives a white precipitate on adding silver nitrate solution. A on reacting with alcoholic $KOH$ gives compound $B$ as the main product. B on ozonolysis gives $C$ and $D$. $ C$ gives Cannizaro reaction but not aldol condensation. $D$ gives aldol condensation but not Cannizaro reaction. $A$ is :

asked Sep 29, 2015 by meena.p

1 answer

In the equation below, value of A is

asked Sep 29, 2015 by meena.p

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The optically inactive compound from the following is :

asked Sep 29, 2015 by meena.p

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$1.4\; g$ of an organic compound was digested according to Kjeldahls method and the ammonia evolved was absorbed in $60\; mL$ of $M/10\; H_2SO_4$ solution. The excess sulphuric acid required $20\;mL$ of $M/10\;NaOH$ solution for neutralization. The percentage of nitrogen in the compound is :

asked Sep 28, 2015 by meena.p

1 answer

Photochemical smog consists of excessive amount of X, in addition to aldehydes, ketones, peroxy acetyl nitrile (PAN), and so forth. X is :

asked Sep 28, 2015 by meena.p

1 answer

The correct statement on the isomerism associated with the following complex ions,$ (a) [Ni(H_2O)_5NH_3]^{2+},\\ (b) [Ni(H_2O)_4(NH_3)_2]^{2+} \;and\\ (c) [Ni(H_2O)_3(NH_3)_3]^{2+}\; is :$

asked Sep 28, 2015 by meena.p

1 answer

Which molecule/ion among the following cannot act as a ligand in complex compounds ?

asked Sep 28, 2015 by meena.p

1 answer

Which molecule/ion among the following cannot act as a ligand in complex compounds ?

asked Sep 28, 2015 by meena.p

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An aqueous solution of a salt X turns blood red on treatment with $SCN^{-}$ and blue on treatment with $K_4[Fe(CN)_6]$. $X$ also gives a positive chromyl chloride test. The salt X is :

asked Sep 28, 2015 by meena.p

1 answer

The geometry of $XeOF_4$ by $VSEPR$ theory is

asked Sep 28, 2015 by meena.p

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The least number of oxyacids are formed by :

asked Sep 28, 2015 by meena.p

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The correct order of thermal stability of hydroxides is :

asked Sep 28, 2015 by meena.p

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Permanent hardness in water cannot be cured by :

asked Sep 28, 2015 by meena.p

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In the isolation of metals, calcination process usually results in :

asked Sep 28, 2015 by meena.p

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In the long form of the periodic table, the valence shell electronic configuration of $5s^2, 5p^4$ corresponds to the element present in :

asked Sep 28, 2015 by meena.p

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The following statements relate to the adsorption of gases on a solid surface. Identify the incorrect statement among them :

asked Sep 28, 2015 by meena.p

1 answer

The reaction $2N_2O_5(g) \to 4NO_2(g) +O_2(g)$ follows first order kinetics . The pressure of a vessel containing only $N_2O_5$ was found to increase from $50 \;mm$ Hg to $87.5\;mm$ Hg in 30 min. The pressure exerted by the gas after 60 min will be (Assume temperature remains constant ) :

asked Sep 28, 2015 by meena.p

1 answer

A variable, opposite external potential $(E_{ext})$ is applied to the cell $Zn|Zn^{2+} (1 M) || Cu^{2+} (1 M) | Cu,$ of potential $1.1\; V$. When $E_{ext} < 1.1 V$ and $E_{ext} > 1.1 V,$ respectively electrons flow from :

asked Sep 28, 2015 by meena.p

1 answer

Gaseous $N_2O_4$ dissociate into gaseous $NO_2$ according to the reaction $N_2O_4(g) \to 2NO_2(g)$. At 300 K and 1 atm pressure , the degree of dissociation of $N_2O_4$ is $0.2$. If one mole of $N_2O_4$ gas is contained in a vessel, then the density of the equilibrium mixture is :

asked Sep 28, 2015 by meena.p

1 answer

A solution at $20^{\circ}C$ is composed of $1.5\;mol$ of benzene and $3.5\; mol$ of toluene. If the vapour pressure of pure benzene and pure toluene at this temperature are $74.7$ torr and $22.3$ torr, respectively, then the total vapour pressure of the solution and the benzene mole fraction in equilibrium with it will be, respectively :

asked Sep 28, 2015 by meena.p

1 answer

The heat of atomization of methane and ethane are $360 \;kJ/mol$ and $620 kJ/mol,$ respectively. The longest wavelength of light capable of breaking the C - C bond is (Avogadro number=6.02 \times 10^{23},h= 6.62 \times 10^{-34}\;Js)$: h56.62310234 J s) :

asked Sep 28, 2015 by meena.p

1 answer

After understanding the assertion and reason, choose the correct option. Assertion : In the bonding molecular orbital (MO) of $H_2$, electron density is increased between the nuclei. Reason : The bonding $MO$ is which shows destructive interference of the combining electron waves.

asked Sep 28, 2015 by meena.p

1 answer

If the principal quantum number $n=6$, the correct sequence of filling of electrons will be :

asked Sep 28, 2015 by meena.p

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Which of the following is not an assumption of the kinetic theory of gases ?

asked Sep 28, 2015 by meena.p

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A sample of a hydrate of barium chloride weighing $61\;g$ was heated until all the water of hydration is removed . The dried sample weighted $52\;g$ The formula of the hydrated salt is : (atomic mass, Ba=137 amu, Cl=35.5 amu)

asked Sep 28, 2015 by meena.p

1 answer

Diameter of a steel ball is measured using a Vernier callipers which has divisions of $0.1\;cm$ on its main scale (MS) and $10$ divisions of its vernier scale (VS) match $9$ divisions on the main scale. Three such measurements for a ball are given as : If the zero error is 20.03 cm, then mean corrected diameter is :

asked Sep 28, 2015 by meena.p

1 answer

In an unbiased n-p junction electrons diffuse from n - region to p - region because :

asked Sep 28, 2015 by meena.p

1 answer

If one were to apply Bohr model to a particle of mass m and charge q moving in a plane under the influence of a magnetic field B, the energy of the charged particle in the nth level will be :

asked Sep 28, 2015 by meena.p

2 answers

de-Broglie wavelength of an electron accelerated by a voltage of $50\; V$ is close to $(|e|=1.6 \times 10^{-19}\; C, m_e=9.1 \times 10^{-31}\; kg,h=6.6 \times 10^{-34}\;Js)$ :

asked Sep 25, 2015 by meena.p

1 answer

A telescope has an objective lens of focal length $150\;cm$ and an eyepiece of focal length $5\;cm$. If a $50\; m$ tall tower at a distance of 1 km is observed through this telescope in normal setting, the angle formed by the image of the tower is $\theta$, then $\theta$ is close to :

asked Sep 25, 2015 by meena.p

1 answer

A parallel beam of electrons travelling in x-direction falls on a slit of width d (see figure). If after passing the slit, an electron acquires momentum $P_y$ in the y-direction then for a majority of electrons passing through the slit (h is Plancks constant) :

asked Sep 25, 2015 by meena.p

1 answer

You are asked to design a shaving mirror assuming that a person keeps it $10\; cm$ from his face and views the magnified image of the face at the closest comfortable distance of $25\; cm$. The radius of curvature of the mirror would then be :

asked Sep 25, 2015 by meena.p

1 answer

An electromagnetic wave travelling in the x-direction has frequency of $2 \times 10^{14}\; Hz$ and electric field amplitude of $27 \;Vm^{-1}$. From the options given below, which one describes the magnetic field for this wave ?

asked Sep 25, 2015 by meena.p

1 answer

In the circuits (a) and (b) switches $S_1$ and $S_2$ are closed at $t=0$ and are kept closed for a long time. The variation of currents in the two circuits for $t \geq 0$ are roughly shown by (figures are schematic and not drawn to scale) :

asked Sep 25, 2015 by meena.p

1 answer

When current in a coil change from $5\;A$ to $2\;A$ in $0.1\;s$, an average voltage of $50\;V$ is produced . The self- inductance of the coil is :

asked Sep 25, 2015 by meena.p

1 answer

A 25 cm long solenoid has radius 2 cm and 500 total number of turns. It carries a current of 15 A. If it is equivalent to a magnet of the same size and magnetization $\overrightarrow{M}$ (magnetic moment /volume), then $|\overrightarrow{M}| $ is :

asked Sep 25, 2015 by meena.p

1 answer

A proton (mass m) accelerated by a potential difference V flies through a uniform transverse magnetic field B. The field occupies a region of space by width d. If $\alpha$ be the angle of deviation of proton from initial direction of motion (see figure), the value of $\sin \alpha$ will be :

asked Sep 25, 2015 by meena.p

1 answer

A $10\;V$ battery with internal resistance $1V$ and a $15V$ battery with internal resistance $0.6V$ are connected in parallel to a voltmeter (see figure). The reading in the voltmeter will be close to :

asked Sep 25, 2015 by meena.p

1 answer

Suppose the drift velocity $v_d$ in a material varied with the applied electric field $E$ as $v_d \alpha E$ ; .Then $V - I$ graph for a wire made of such a material is best given by :

asked Sep 25, 2015 by meena.p

1 answer

If the capacitance of a nanocapacitor is measured in terms of a unit 'u' made by combining the electronic charge e, Bohr radius $a_0$, Plancks constant h and speed of light c then :

asked Sep 25, 2015 by meena.p

1 answer

Shown in the figure are two point charges $+Q$ and $-Q$ inside the cavity of a spherical shell. The charges are kept near the surface of the cavity on opposite sides of the centre of the shell. If $\sigma_1$ is the surface charge on the inner surface and $Q_1$ net charge on it and $\sigma_2$ the surface charge on the outer surface and $Q_2$ net charge on it then :

asked Sep 25, 2015 by meena.p

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A thin disc of radius $b=2a$ has a concentric hole of radius a in it (see figure). It carries uniform surface charge s on it. If the electric field on its axis at height $h (h<<a)$ from its centre is given as 'Ch' then value of C is :

asked Sep 25, 2015 by meena.p

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