Recent questions tagged physical-chemistry

Statement 1: Band gap in germanium is small. Statement 2 : The energy spread of each germanium atomic energy level in infinitesimally small.

asked Apr 4, 2014 by meena.p

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Statement 1: p-hydroxybenzonic acid has a lower boiling point than $O- hydroxybenzonic acid. Statement 2: O-Hydroxybenzonic acid has intramolecular hydrogen bonding.

asked Apr 4, 2014 by meena.p

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Statement 1: $LiCl$ is predominantly a covalent compound. Statement 2: Electronegativity difference between $Li$ and $Cl$ is too small.

asked Apr 4, 2014 by meena.p

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Which one is most ionic?

asked Apr 4, 2014 by meena.p

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According to molecular orbitals theory which of the following statement about the magnetic character and bond order is correct regarding $O_2^{+}$?

asked Apr 4, 2014 by meena.p

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Among the following compounds the one that is polar and has the central atom with $SP^2$ hybridisation is

asked Apr 4, 2014 by meena.p

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The type of hybrid orbitals used by the chlorine atom in $ClO^{-}_2$ is

asked Apr 3, 2014 by meena.p

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If a molecule $M X_3$ has zero dipole moment. the sigma bonding orbitals used by M. (atomic number <21) are

asked Apr 3, 2014 by meena.p

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The rate law of a reaction $A+B \to $ product is rate $=K [A]^n[B]^m$. On doubling the concentration of A and halving the concentration of B. Thr ratio of new rate to the earlier rate of reaction will be :

asked Apr 3, 2014 by meena.p

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Units of rate constant of first and zero order reaction in terms of molarity M are respectively :

asked Apr 3, 2014 by meena.p

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$t \large\frac{1}{4}$ can be taken as the time taken for concentration of reactant to drop to $\large\frac{3}{4}$ of its initial value. If the rate constant for a first order reaction is $K,$ then $t \large\frac{1}{4}$ can be written as

asked Apr 3, 2014 by meena.p

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The half - life period of a first order chemical reaction is $6.93$ minutes. The time required for the completion of $99\%$ of the chemical reaction will be $(\log 2 =0.301)$

asked Apr 3, 2014 by meena.p

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If I is the intensity of absorbed light and C is the concentration of AB for the photochemical process $AB+hr \to AB^ x$ the rate of formation of $AB^x$is directly proportional X :

asked Apr 3, 2014 by meena.p

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The temperature coefficient of a reaction is :

asked Apr 3, 2014 by meena.p

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The lightening of fire files is :

asked Apr 3, 2014 by meena.p

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Large increase in the rate of reaction due to rise in temperature is due to :

asked Apr 3, 2014 by meena.p

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One Einstein = N $\times$ quanta of energy where N is :

asked Apr 3, 2014 by meena.p

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For an endothermic reaction where $\Delta H$ represents the enthalpy of the reaction in $kj/mol$. the minimum value for the energy of activation will be

asked Apr 3, 2014 by meena.p

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The rate of a reaction gets doubled when the temperature changes from $7^{\circ}C$ to $17^{\circ}$ . By what factor will it change for the temperature change from $17^{\circ}C$ to $27^{\circ}C$

asked Apr 3, 2014 by meena.p

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For a first order reaction , the plot of t against log C gives a straight with slope equal to :

asked Apr 3, 2014 by meena.p

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Half- life $(t_1)$ of the first order reaction and half-life $(t_2)$ of the second order reaction are equal. Hence ratio of the rate of the rate at te start of the reaction.

asked Apr 3, 2014 by meena.p

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The chemical reaction $2O_3 \to 3O_2$ proceeds as follows : $ O_3 \rightleftharpoons O_2+O ......(fast) \qquad O+O_3 \to 2O_2 ....(slow)$. The rate law expression should be :

asked Apr 3, 2014 by meena.p

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The rate of the elementary reaction, $2NO+O_2 \to 2NO_2$ when the volume of the reaction vessel is doubled

asked Apr 3, 2014 by meena.p

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Which of the following hydrocarbons has the lowest dipole moment?

asked Apr 3, 2014 by meena.p

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Hybridisation is defined as the phenomenon of mixing of orbitals of nearly the same energy so as to redistribute their energies and to give rise to new orbitals of equivalent energy. It is the valence shell atomic which get hybridised one of the electrons from an orbital in the ground state electronic configuration of the atom gets promoted to the next available orbital of higher energy resulting in an excited state electronic configuration with the appropriate number of half filled orbitals. The orbitale in the excited state undergo hybridisation giving hybrid orbilats of equivalent energy. Hybrid orbitals generally from either bonds or contain lone pair of electrons, they do not form $\pi$ bonds. Depending on the type of orbitals used the hybridisation may be categorized as $SP$(linear), $SP^2$ (trigonal planar ), $SP^3$(tetrahedral), $SP^3d$(trigonal bipyramidal), $SP^3d^2$(Octahedral), $SP^3d^3$ (Pentagonal bipyramid ).The strength of bonds formed by $S-S,P-P$ and $S-P$ overlap is in the order of

asked Apr 3, 2014 by meena.p

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Hybridisation is defined as the phenomenon of mixing of orbitals of nearly the same energy so as to redistribute their energies and to give rise to new orbitals of equivalent energy. It is the valence shell atomic which get hybridised one of the electrons from an orbital in the ground state electronic configuration of the atom gets promoted to the next available orbital of higher energy resulting in an excited state electronic configuration with the appropriate number of half filled orbitals. The orbitale in the excited state undergo hybridisation giving hybrid orbilats of equivalent energy. Hybrid orbitals generally from either bonds or contain lone pair of electrons, they do not form $\pi$ bonds. Depending on the type of orbitals used the hybridisation may be categorized as $SP$(linear), $SP^2$ (trigonal planar ), $SP^3$(tetrahedral), $SP^3d$(trigonal bipyramidal), $SP^3d^2$(Octahedral), $SP^3d^3$ (Pentagonal bipyramid ). Atomic orbitals of carbon in graphite have

asked Apr 3, 2014 by meena.p

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Hybridisation is defined as the phenomenon of mixing of orbitals of nearly the same energy so as to redistribute their energies and to give rise to new orbitals of equivalent energy. It is the valence shell atomic which get hybridised one of the electrons from an orbital in the ground state electronic configuration of the atom gets promoted to the next available orbital of higher energy resulting in an excited state electronic configuration with the appropriate number of half filled orbitals. The orbitale in the excited state undergo hybridisation giving hybrid orbilats of equivalent energy. Hybrid orbitals generally from either bonds or contain lone pair of electrons, they do not form $\pi$ bonds. Depending on the type of orbitals used the hybridisation may be categorized as $SP$(linear), $SP^2$ (trigonal planar ), $SP^3$(tetrahedral), $SP^3d$(trigonal bipyramidal), $SP^3d^2$(Octahedral), $SP^3d^3$ (Pentagonal bipyramid ). The non - linear structure is assumed by

asked Apr 3, 2014 by meena.p

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Hybridisation is defined as the phenomenon of mixing of orbitals of nearly the same energy so as to redistribute their energies and to give rise to new orbitals of equivalent energy. It is the valence shell atomic which get hybridised one of the electrons from an orbital in the ground state electronic configuration of the atom gets promoted to the next available orbital of higher energy resulting in an excited state electronic configuration with the appropriate number of half filled orbitals. The orbitale in the excited state undergo hybridisation giving hybrid orbilats of equivalent energy. Hybrid orbitals generally from either bonds or contain lone pair of electrons, they do not form $\pi$ bonds. Depending on the type of orbitals used the hybridisation may be categorized as $SP$(linear), $SP^2$ (trigonal planar ), $SP^3$(tetrahedral), $SP^3d$(trigonal bipyramidal), $SP^3d^2$(Octahedral), $SP^3d^3$ (Pentagonal bipyramid ). Which one of the following species is diamagnetic ?

asked Apr 3, 2014 by meena.p

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Hydrogen bonding is an electrostatic attraction between covalently bonded hydrogen atom of one molecular with highly electronegative atom (N or F or O) of the same molecular or another molecule. or another molecular .It is of two types -(i) Intermolecular hydrogen bonding where molecular association is caused due to interaction of $H-atom$ of one molecular and N or F or 0-atoms of different molecules. (ii) Intramolecular hydrogen bonding where hydrogen bonding occurs between H atom and N or F or O-atom of the same molecule. Intermolecular hydrogen bonding increases the boiling point of the compound and its solubility in water , whereas intramolecular hydrogen bonding decreases the boiling point of the compound and solubility in water. Which one among the following does not have the hydrogen bond?

asked Apr 2, 2014 by meena.p

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Hydrogen bonding is an electrostatic attraction between covalently bonded hydrogen atom of one molecular with highly electronegative atom (N or F or O) of the same molecular or another molecule. or another molecular .It is of two types -(i) Intermolecular hydrogen bonding where molecular association is caused due to interaction of $H-atom$ of one molecular and N or F or 0-atoms of different molecules. (ii) Intramolecular hydrogen bonding where hydrogen bonding occurs between H atom and N or F or O-atom of the same molecule. Intermolecular hydrogen bonding increases the boiling point of the compound and its solubility in water , whereas intramolecular hydrogen bonding decreases the boiling point of the compound and solubility in water.Highest viscosity is exhibited by

asked Apr 2, 2014 by meena.p

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Hydrogen bonding is an electrostatic attraction between covalently bonded hydrogen atom of one molecular with highly electronegative atom (N or F or O) of the same molecular or another molecule. or another molecular .It is of two types -(i) Intermolecular hydrogen bonding where molecular association is caused due to interaction of $H-atom$ of one molecular and N or F or 0-atoms of different molecules. (ii) Intramolecular hydrogen bonding where hydrogen bonding occurs between H atom and N or F or O-atom of the same molecule. Intermolecular hydrogen bonding increases the boiling point of the compound and its solubility in water , whereas intramolecular hydrogen bonding decreases the boiling point of the compound and solubility in water. The maximum possible number of hydrogen bonds in which a water molecule can participate is

asked Apr 2, 2014 by meena.p

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Hydrogen bonding is an electrostatic attraction between covalently bonded hydrogen atom of one molecular with highly electronegative atom (N or F or O) of the same molecular or another molecule. or another molecular .It is of two types -(i) Intermolecular hydrogen bonding where molecular association is caused due to interaction of $H-atom$ of one molecular and N or F or 0-atoms of different molecules. (ii) Intramolecular hydrogen bonding where hydrogen bonding occurs between H atom and N or F or O-atom of the same molecule. Intermolecular hydrogen bonding increases the boiling point of the compound and its solubility in water , whereas intramolecular hydrogen bonding decreases the boiling point of the compound and solubility in water. The hydrogen bond is strongest in

asked Apr 2, 2014 by meena.p

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The species which contain an odd number of valence electrons and are paramagnetic are

asked Apr 2, 2014 by meena.p

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Intramolecular hydrogen bonds occur is (i) 2- chlorophenol (ii) Salicylic acid (iii) para nitrophenol (iv) none of these

asked Apr 2, 2014 by meena.p

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Which of the following species contain covalent coordinate bonds? $(i)\; AlCl_3 \\ (ii)\;CO \\ (iii)\;[Fe(CN)_6]^{4-} \\ (iv)\; NO_3^{-}$

asked Apr 2, 2014 by meena.p

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Which of the following have identical bond order? $(i)\; CN^{-} \\ (ii)\;NO_2^{-} \\ (iii)\;NO^{+} \\ (iv)\; CN^{+}$

asked Apr 2, 2014 by meena.p

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Which of the following conditions apply to resonating structures? (i) Identical arrangements of atoms (ii) Nearly same energy content (iii) Identical number of bonds (iv) Same number of unpaired electrons

asked Apr 2, 2014 by meena.p

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Which of the following are diamagnetics ? $(i)\;C_2 \\ (ii)\;He_2 \\(iii)\;Li_2 \\(iv)\;N_2 $

asked Apr 2, 2014 by meena.p

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In which of the following the hybrid orbitals of the central atom have the same s-characters ? $(i)\;CH_4 \qquad (ii)\; Ni(CO) \qquad (iii)\;SF_4 \qquad (iv) [Ni(CN)_4]^{2-} $

asked Apr 2, 2014 by meena.p

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Consider the reaction ,$2A +B \to products$ when concentration of B alone was doubled , the half -life did not change . When the concentration of A alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is :

asked Apr 2, 2014 by meena.p

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The time for half life period of a certain reaction. A - products is 1 hour when initial concentration of the reactant A is $2.0\; mol\; L^{-1}$, how much time does it take for its concentration to come from $0.50$ to $ 0.25\;mol L^{-1}$ if it is a zero order reaction ?

asked Apr 2, 2014 by meena.p

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The $ONO$ bond angle is maximum in

asked Apr 2, 2014 by meena.p

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Which of the following are isoelectronic and isostructural ? $NO_3^{-},CO_3^{2-},ClO_3^{-}, SO_3$

asked Apr 2, 2014 by meena.p

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Which is most viscous?

asked Apr 2, 2014 by meena.p

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The electronegativities of $F,Cl,Br$ and $I$ are $4.0,3.0,2.8$ and $2.5$ respectively. Hydrogen halide with a high percentage of ionic character is

asked Apr 2, 2014 by meena.p

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$N_2$ forms $Ncl_3$ whereas P can form both $Pcl_3$ and $PCl_5$ why ?

asked Apr 2, 2014 by meena.p

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In III A group ,Tl (Thalium) shows stable +1 oxidation state, while boron shows stable +3 oxidation state. It is due to

asked Apr 2, 2014 by meena.p

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Which one of the following oxides is expected to exhibit paramagnetic behaviour ?

asked Apr 2, 2014 by meena.p

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Which of the species is diamagnetic ?

asked Apr 2, 2014 by meena.p

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Correct order of bond length is

asked Apr 1, 2014 by meena.p

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