Recent questions tagged 1991

Nucleides having different mass number and different atomic number, but the same number of neutrons are called ...................... .

asked Sep 12, 2013 by meena.p

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The coordinating number of the ions in the CsCI crystal lattice is ................. .

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A few drops of an organic compound (liquid) are added to schiff's reagent. A pink colour is produced. The organic compound is ................. .

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$0.1\;M\;HCL$ solution is diluted by $100\;times$. The pH of the solution so formed is .............. .

asked Sep 12, 2013 by meena.p

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The kinetic energy of 8g of $H_2$ at $27^{\circ}C$ is ................. times more than the kinetic energy of $8g$ of $O_2$ at the same temperature.

asked Sep 12, 2013 by meena.p

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The weight of oxalic acid crystals $H_2C_2O_2.2H_2O$ required to prepare $500\;mL$ of $0.2\;N$ solution is ................... .

asked Sep 12, 2013 by meena.p

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Aqueous solution of $FeCl_3$ is acidic because of .............. .

asked Sep 12, 2013 by meena.p

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The half life of a radioactive substance is $100$ sec. It's disintegration constant is ..................... .

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In the reaction $^{19}_8 O+_1H^2 \to ^{18}_8O+X,X$ is ................... .

asked Sep 12, 2013 by meena.p

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The reaction between .............. Baeyer reagent gives ethylene glycol.

asked Sep 12, 2013 by meena.p

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Water has a higher boiling point than corresponding hydrides $H_2S,H_2Se$ and $H_2Te$. This is because of ............. in water.

asked Sep 12, 2013 by meena.p

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The normal boiling point of, $CS_2,H_2O$ and $CCl_4$ are $41.3^{\circ}C,100^{\circ}C$ and $77^{\circ}C$ respectively. The liquid in which the inter molecular forces are the weakest is ................ .

asked Sep 12, 2013 by meena.p

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The magnetic quantum number $m$ for the outermost electron in the Na atom is .............. .

asked Sep 12, 2013 by meena.p

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Besides $SiO_2$ and $Al_2O_3$ the other major ingradient in portland cement is ................. .

asked Sep 12, 2013 by meena.p

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Refer the below equation:

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The number of $\sigma $ bonds in the ethylene molecule is ............... .

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The mass number of a nuclide is 125. Its nuclear radius is .................. fermi.

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The maximum number of electron that can be accommodated in all the orbitals for which $l=3$, is .............. .

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Reduction of acetaldehyde in presence of $LiAlH_4$ gives ...............

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Among the $SO_2,H_2SO_4$ and sodium thiosuphate, sulphur has the highest oxidation state in .............. .

asked Sep 12, 2013 by meena.p

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The non-metallic element present in the mineral cryolite is ............... .

asked Sep 12, 2013 by meena.p

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In the reaction $C_2O_4^{2-}+MnO^{-}_4+H^{+} \to H_2O+Mn^{2+}+CO_2$ the reductant is ............... .

asked Sep 12, 2013 by meena.p

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Chloroform reacts with $HNO_3$ ............... .

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The process of slow cooling of glass is called .............. .

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Phosgene is formed when ................. is exposed to air and sun light.

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If the pressure and the absolute temperature of a given mass of gas are doubled, the new volume will be ................ the initial volume.

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Among the alkali metals, the metal with the highest ionisation potential is ................ .

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The conjugate base of $HSO^-_4$ ion is ............. .

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The rate of diffusion of He is .............. the rate of diffusion of $CH_4$.

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The number of moles of barium carbonate which contains $1.5$ moles of $O_2$ atoms is .................. .

asked Sep 12, 2013 by meena.p

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When an electron in an excited hydrogen atom jumps from an energy level for which $n=5$ level for which $n=2$ the spectral line is observed in the .................. series of the hydrogen spectrum.

asked Sep 12, 2013 by meena.p

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The reagent that has action on glass is :

asked Sep 11, 2013 by meena.p

1 answer

One atom of $^{39}_{19} K$ contains :

asked Sep 11, 2013 by meena.p

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$9.8\;g$ of $H_2 SO_4$ is present in two liters of a solution. The molarity of the solution is :

asked Sep 11, 2013 by meena.p

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Which of the following oxides of nitrogen is anhydride of $HNO_3$ ?

asked Sep 11, 2013 by meena.p

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The bonds in $K_4 Fe(CN)_6$ are:

asked Sep 11, 2013 by meena.p

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The $pK_a$ of a certain weak acid is $4.0.$ What should be the [salt] to [acid] ratio, if we have to prepare a buffer with a $pH=5$ using the acid and one of the salts?

asked Sep 11, 2013 by meena.p

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Which of the following statements about the halogen is correct?

asked Sep 11, 2013 by meena.p

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In which one of the following reactions does the heat change represent the heat of formation of water?

asked Sep 11, 2013 by meena.p

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The relative lowering of vapour pressure is equal to:

asked Sep 11, 2013 by meena.p

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Three faradays of electricity was passed through an aqueous solution of iron (II) bromide. The weight of iron metal (at. wt.= 56) deposited at the cathode is (in grams):

asked Sep 11, 2013 by meena.p

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The rms velocity of an ideal gas at $27^{\circ}C$ is $0.3\;m/s$. Its rms velocity at $927^{\circ}C$(in m/s.) is :

asked Sep 11, 2013 by meena.p

1 answer

The energy of the electron in the hydrogen atom is given by the expression:

asked Sep 11, 2013 by meena.p

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A gaseous mixture contains $56\;g$ of $N_2,44\;g $ of $\; CO_2$ and $16\; g$ of $CH_4$. The total pressure of the mixture is $720 \;mm$ Hg. The partial pressure of $CH_4$ is :

asked Sep 11, 2013 by meena.p

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Aniline is treated with $NaNO_2$ and $HCl$ at $0^{\circ} C$, the product formed is

asked Sep 11, 2013 by meena.p

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Which one of the following series of lines is found in the UV region of atomic spectrum of hydrogen?

asked Sep 11, 2013 by meena.p

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A ratio isotope has a half life 10 days. If today there is 125 g of it left, what was its weight 40 days earlier?

asked Sep 11, 2013 by meena.p

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When $4p$ orbital in any atom is filled completely, the next electron goes in

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An organic compound has an empirical formula $CH_2O$. Its vapour density is 45. The molecular formula of compound is :

asked Sep 11, 2013 by meena.p

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Which of the gases contain the same number of molecules as that of $16\; g$ oxygen ?

asked Sep 11, 2013 by meena.p

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