Recent questions tagged 2008

World Summit on Sustainable Development (2002) was held in:

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The two subunits of ribosome remain united at a critical ion level of :

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Which one of the following is the correct percentage of the two (out of the total of 4) greenhouse gases that contribute to the total global warming ?

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Which one of the following is not observed in biodiversity hotspots ?

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The length of different internodes in a culm of sugarcane is variable because of:

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Senescence as an active developmental cellular process in the growth and functioning of a flowering plant, is indicated in:

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A competitive inhibitor of succinic dehydrogenase is :

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If 'a' stands for the edge length of the cubic 3 systems : simple cubic, body centered cubic and face centered cubic, then the ratio of radii of the spheres in these systems will be respectively.

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Standard free energies of formation (in kJ/mol) at 298 K are -237.2, -394.4 and -8.2 for $H_2O(l)$, $CO_2 (g)$ and pentane(g) respectively The value of $E^o$ cell for the pentane-oxygen fuel cell is:

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A strong base can abstract an $\alpha$-hydrogen from:

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The rate constants $k_1$ and $k_2$ for two different reactions are $10^{16}.e^ {^\frac{-2000}{T}}$ and $10^{15}.e^{^\frac{-1000}{T}}$ respectively, the temperature at which $k_1$=$k_2$,, is:

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Number of moles of $MnO{_4}{^-}$ required to oxidize one mole of ferrous oxalate completely in acidic medium will be :

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With which one of the following elements silicon should be doped so as to give p-type of semiconductor?

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The correct order of increasing bond angles in the following triatomic species is :

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In a $S_N2$ substitution reaction of the type $R-Br+Cl^-\underrightarrow{DMF} R-Cl+Br^-$ Which one of the following has the highest relative rate ?

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Which of the following statements is not correct ?

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Green chemistry means such reactions which -

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The measurement of the electron position is associated with an uncertainty in momentum, which is equal to $1 \times 10^{ –18}$ g $cm s^{ –1}$. The uncertainty in electron velocity is : (Mass of an electron is $9 \times10^{–28}$ g)

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For the gas phase reaction, $PCl_5(g) \rightleftharpoons PCl_3(g) + Cl_2(g)$ Which of the following conditions are correct ?

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In a reaction of aniline a coloured product (C) was obtained. The structure of (C) would be -

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Which one of the following statements is not true ?

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How many moles of lead (II) chloride will be formed from a reaction between 6.5 g of PbO and 3.2 g of HCl ?

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Four diatomic species are listed below in different sequences. Which of these presents the correct order of their increasing bond order ?

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Which one of the following is most reactive towards electrophilic attack ?

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The correct order of decreasing second ionization enthalpy of Ti = 22, V = 23, Cr = 24 and Mn = 25 is -

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On the basis of the following Eº values, the strongest oxidizing agent is : $[Fe(CN)_6]^{4-}\rightarrow[Fe(CN)_6]^{3-}+e^{-1},E^o=-0.35v$ $Fe^{2+}\rightarrow Fe^{3+}+e^{-1},E^o=-0.77v$

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How many stereoisomers does this molecule have $CH_3CH = CHCH_2 CHBrCH_3$

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If uncertainty in position and momentum are equal, then uncertainty in velocity is -

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If the concentration of $OH^-$ ions in the reaction, $Fe(OH)_3(S)\rightleftharpoons Fe^{3+}(aq.)+3OH^-(aq)$ is decreased by $1\frac{1}{4}$ times, then equilibrium concentration of $Fe^{3+ }$will increase by -

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The bromination of acetone that occurs in acid solution is represented by this equation. $CH_3COCH_3(aq.)+Br_2(aq.)\longrightarrow CH_3COCH_2Br(aq)+H^+(aq)+Br^-(aq.)$ These kinetic data were obtained from given reaction concentrations. Initial rate, disappearance of $Br_2, Ms^{-1}$ $5.7 \times 10^{-5}$ $5.7 \times 10^{-5}$ $1.2 \times 10^{-4}$ $3.1 \times 10^{-4}$ Based on these data, the rate equation is :

asked Jul 26, 2018 by pady_1

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The dissociation equilibrium of a gas $AB_2$ can be represented as : $2AB_2 (g)\rightleftharpoons 2AB(g) + B_2 (g)$ The degree of dissociation is 'x' and is small s compared to 1. The expression relating the degree of dissociation (x) with equilibrium constant $K_p$ and total pressure P is -

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If a gas expands at constant temperature, it indicates that :

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Two thin lenses of focal lengths $f_1$ and $f_2$ are in contact and coaxial. The power of the combination is -

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A point performs simple harmonic oscillation of period T and the equation of motion is given by x = a sin ($(\omega t+\frac{\pi}{6})$). After the elapse of what fraction of the time period the velocity of the point will be equal to half of its maximum velocity ?

asked Jul 26, 2018 by pady_1

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The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of the incident radiation for which the stopping potential is 5 V lies in the :

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Two radioactive materials $X_1$ and $X_2$ have decay constants $5\lambda$ and $\lambda$ respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of $X_1$ to - that of $X_2$ will be $\frac{1}{e}$ after a time

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A current of 3 amp. flows through the $2\Omega$ resistor shown in the circuit. The power dissipated in the $5\Omega$ resistor is -

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Which two of the following five physical parameters have the same dimensions ? (a) Energy density (b) Refractive index (c) Dielectric constant (d) Young’s modulus (e) Magnetic field

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Curie temperature is the temperature above which -

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A wire of a certain material is stretched slowly by ten percent. Its new resistance and specific resistance become respectively -

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A closed loop PQRS carrying a current is placed in a uniform magnetic field. If the magnetic forces on segments PS, SR and RQ are $F_1$ ,$ F_2$ and $F_3$ respectively and are in the plane of the paper and along the directions shown, the force on the segment QP is :

asked Jul 26, 2018 by pady_1

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A boy is trying to start a fire by focusing Sunlight on a piece of paper using an equiconvex lens of focal length 10 cm. The diameter of the Sun is $1.39 \times 10^ 9$ m and its mean distance from the earth is $1.5 \times 10^{11}$ m. What is the diameter of the Sun’s image on the paper ?

asked Jul 26, 2018 by pady_1

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The wave described by y = 0.25 sin (10 $\pi X$ – 2$\pi f$), where x and y are in metres and t in seconds, is a wave travelling along the -

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On a new scale of temperature (which is linear) s and called the W scale, the freezing and boiling points of water are 39º W and 239º W respectively. What will be the temperature on the new scale, corresponding to a temperature of 39ºC on the Celsius scale ?

asked Jul 26, 2018 by pady_1

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In the circuit shown, the current through the 4$\Omega$ resistor is 1 amp when the points P and M are connected to a D.C. voltage source. The potential difference between the points M and N is

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If Q, E and W denote respectively the heat added, change in internal energy and the work done by a closed cycle process, then :

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Two periodic waves of intensities $I_1$ and $I_2$ pass through a region at the same time in the same direction. the sum of the maximum and minimum intensities is -

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A particle shows distance-time curve as given in this figure. The maximum instantaneous velocity of the particle is around the point :

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A particle moves in a straight line with a constant acceleration. It changes its velocity from 10 $ms^{–1}$ to 20 $ms^{–1}$ while passing through a distance 135 m in t second. The value of t is -

asked Jul 26, 2018 by pady_1

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If M (A, Z), $M_p$ and $M_n$ denote the masses of the nucleus $^{A}_ {Z} X$ , proton and neutron respectively in units of u (1u = 931.5 Me$\frac{V}{C}^2$ ) and BE represents its bonding energy in MeV, then -

asked Jul 26, 2018 by pady_1

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