Recent questions in Chemistry

An LPG cylinder contain 15kg of butane gas at $27^{\large\circ}C$ and 10 bar pressure. The cylinder linked and it was found that after 4 days , the mass of the gas left in cylinder was only 10 kg. How much drop in pressure was occured in each day?

asked Mar 1, 2014 by sharmaaparna1

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Densities of two gases of same molecular weight are in the ratio 1:2 and their temperature are in the ratio 2:1 then the ratio of their respective pressures is

asked Mar 1, 2014 by sharmaaparna1

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The density of a gas at STP is 2.68g/L . The gas may be

asked Mar 1, 2014 by sharmaaparna1

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If the pressure of $N_2/H_2$ mixture in a closed vessel is 100 atm and 20% of the mixture then reacts , the pressure at the same temperature would be

asked Mar 1, 2014 by sharmaaparna1

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A gas is heated through $1^{\large\circ}C$ in a closed vessel and so the pressure increases by $0.4\%$ . The initial temperature of the gas was

asked Mar 1, 2014 by sharmaaparna1

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Volume coefficient according to charle's law is

asked Mar 1, 2014 by sharmaaparna1

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To expel half the mass of air from a large flask at $27^{\large\circ}C$ , it must be heated to

asked Mar 1, 2014 by sharmaaparna1

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The concentration of $O_2$ and $CO_2$ is variable but on the average , $100\;mL$ blood contains 0.02g of $O_2$ and $0.08\;g$ of $CO_2$. Calculate the Volume of $O_2$ and $CO_2$ at $1\; atm$ and body temperature $37^{\large\circ}C$ assuming $10$ litre blood in human body.

asked Mar 1, 2014 by sharmaaparna1

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The enthalpy of sublimation of iodine is 62.8 kJ/mol. The bond dissociation energies for $Cl_2, I_2$ and ICl are 242.3, 151.0 and 211.3 kJ/mol, respectively. The standard enthalpy of formation of ICl(g) is nearly equal to

asked Mar 1, 2014 by mosymeow_1

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The following equation shows the conversion of limes stone to lime $CaCO_3(s)\longrightarrow CaO(s) + CO_2(g)$. The values of $\Delta H^\circ$ and $\Delta S^\circ$ are $+179.1\; kJ$ and $160.2\; J/K$ respectively at $298\; K$ and $1\; bar$. Assuming that $\Delta H^\circ$ and $\Delta S^\circ$ do not change with temperature, minimum temperature above which conversion of lime stone to lime will be spontaneous is

asked Feb 28, 2014 by mosymeow_1

1 answer

Conversion of A to B is carried out by the following process: $\Delta S(A\rightarrow C)=50eV, \Delta S(C\rightarrow B)=30eV, \Delta S(B\rightarrow D) = 20 eV$, where eV, where eV, is entropy unit, then $\Delta S(A\rightarrow B)$ is

asked Feb 28, 2014 by mosymeow_1

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The enthalpy of hydrogenation of cyclohexene is -119.5 kj/mol. What is the enthalpy of benzene, if its resonance energy is -150.4 kJ/mol?

asked Feb 28, 2014 by mosymeow_1

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For the formation of carbon monoxide (CO) from the elements at 298 K $(\Delta H - \Delta U)$ is (R=8.314 $JK^{-1}mol^{-1}$)

asked Feb 28, 2014 by mosymeow_1

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Given, standard enthalpy of formation $(\Delta _f H^\circ)$ at 298 k for methane is -74.8 kJ/mol. What other information is required to determine the average energy for C-H bond formation would be

asked Feb 28, 2014 by mosymeow_1

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One mole of monoatomic ideal gas at T (K) is expanded from 1 L to 2 L adiabitcally under constant external pressure of 1 atm. The final temperature of gas in kelvin is

asked Feb 28, 2014 by mosymeow_1

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The enthalpy of vaporisation of a liquid is 30 kJ/mol and entropy of vaporisation is 75 $Jmol^{-1}K^{-1}$. What is the boiling point of the liquid at 1 atm?

asked Feb 28, 2014 by mosymeow_1

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Which of the following reactions will define $\Delta H^\circ _f$?

asked Feb 28, 2014 by mosymeow_1

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The enthalpy of combustion of cyclohexane, cyclohexene and $H_2$ are respectively -3920, -3800 and -241 kJ/mol. The heat of hydrogenation of cyclohexane is

asked Feb 28, 2014 by mosymeow_1

1 answer

Given a mole of a non-ideal gas which undergoes a change of state (2.0 atm, 3.0 L 95 K) $\rightarrow$ (4.0 atm, 5.0 L, 245 K) with a change in internalenergy, $\Delta U$ = 30.0 L atm. What will be the change in enthalpy ($\Delta H$) of the process in L atm?

asked Feb 28, 2014 by mosymeow_1

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At $27^\circ C$ the enthalpy change for the transition of liquid water to steam is 30 kJ/mol. What would be the entropy change for the process?

asked Feb 28, 2014 by mosymeow_1

1 answer

Which of the following gas has the highest heat of combustion?

asked Feb 28, 2014 by mosymeow_1

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In a flask colourless $N_2O_4$ is in equilibrium with brown coloured $NO_2$. At equilibrium when the flask is heated at $100^\circ C$, the brown colour deepens and on cooling it becomes less coloured. The changed in enthalpy, $\Delta H$ for this system is

asked Feb 28, 2014 by mosymeow_1

1 answer

For the decomposition of $Ag_2O$ at 298 K. $Ag_2O (s) \longrightarrow 2Ag(s) + \frac{1}{2} O_2(g) \Delta G^\circ$ = 11.21 kJ which of the following statement is true?

asked Feb 28, 2014 by mosymeow_1

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An enantiometrically pure acid is treated with racemix mixture of an alcohol having carbon. The ester formed will be :

asked Feb 28, 2014 by meena.p

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$CH_3,NH_2,OH$ and $F$ in increasing $pk_b $ values are :

asked Feb 28, 2014 by meena.p

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What is the decreasing order of strength of the bases. $OH^{-}.NH_2^{-}.HC \equiv C^{-}$ and $CH_3 -CH_2^{-} $?

asked Feb 28, 2014 by meena.p

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$CH_2 =CH CH_2CH =CH_2 \longrightarrow A,\;A $ is ?

asked Feb 28, 2014 by meena.p

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If $\Delta H^\circ _f$ and $\Delta G ^\circ _f$ of $CH_3OH(g)$ at 298 K is -200.7 kJ/mol and -162 kJ/mol respectively, then absolute entropy of $CH_3OH(g)$ at 298 K is (given absolute entropies of C(s), $H_2(g)$ and $O_2(g)$ at 298 K are 5.7, 130.60 and 205.00 J/mol respectively).

asked Feb 28, 2014 by mosymeow_1

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Devitrification of glass is a process for which change in entropy, $\Delta S$ is

asked Feb 28, 2014 by mosymeow_1

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Br has a low reactivity in $CH_2 =CH-Br$ because (i) of -M effect of bromine (ii) of more electro negativity of bromine (iii) of partial double bond character between $C-Br $ bond. (iv) of the +M effect of bromine.

asked Feb 28, 2014 by meena.p

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Hydrolysis of neopentyl bromide under $SN_1$ process results into

asked Feb 28, 2014 by meena.p

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Which of the following is purified by vacuum distillation ? (i) Glycerine (ii) Glycerol (iii) propane 1,2,3- triol (iv) Ethanol

asked Feb 28, 2014 by meena.p

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Isomers which can not be interconverted through rotation around a single bond are : (i) Conformers ; (ii) diastereomers ; (iii) Enantiomers ; (iv) Positional isomers;

asked Feb 28, 2014 by meena.p

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The major product formed in the reaction given below is

asked Feb 28, 2014 by sreemathi.v

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Dissolution of gases in water is

asked Feb 28, 2014 by mosymeow_1

2 answers

The cannizzaro reaction of benzaldehyde and formaldehyde in the presence of $NaOH$ gives, $(i)\;C_6H_5CH_2OH\; ;(ii)\; C_6H_5COONa\; ; (iii)\; HCOONa \; ; (iv) \;CH_3OH$

asked Feb 28, 2014 by meena.p

1 answer

The major product formed in the reaction given below is

asked Feb 28, 2014 by sreemathi.v

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Which of the following compounds will have only primary and tertiary carbon? (i) Pentane (ii) 2- Methylbutane (iii) 2,3 -Dimethylbutane (iv) 2- Bromo-2-Methylpropane

asked Feb 28, 2014 by meena.p

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Refer the below reaction B is

asked Feb 28, 2014 by sreemathi.v

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Which of the following have zero dipole moment ? $(i)\; H_2;\; (ii)\;HF;\; (iii)\; CH_4; \; (iv) CHCl_3$

asked Feb 28, 2014 by meena.p

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Which of the following statements are correct ?

asked Feb 28, 2014 by meena.p

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Heating of below one produces

asked Feb 28, 2014 by sreemathi.v

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The statement which are correct regarding benzene are : (i) It has $12 \sigma$ and $3 \pi$ bonds. (ii) There is delocalisation of $\pi$ - electrons. (c) $C-C$ bond distance is $1.39 A^{\circ}$ . (d) $C-C$ bond distance is $1.39 A^{\circ}$ and $1.54\;A^{\circ}$ alternatively .

asked Feb 28, 2014 by meena.p

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Which of the following compounds are chiral and resolvable ? $(i) \;[C_6 H_5 N^+(CH_2CH_2CH_3)(C_2H_5)(CH_3)]Br^ - ; \; (ii) C_6H_5N(CH_3)(C_2H_5) ; \\ (iii)\; CH_3CH_2CH (CH_3) (C_2H_5);\; (iv)\; HO_2C- CO_2H$

asked Feb 28, 2014 by meena.p

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Compound A has a molecular formula $C_7H_7NO$ on treatment with $Br_2/KOH$.A gives an amine B which respond to carbylamine test.B on diazotisation and coupling with phenol gives an azo dye.A can be

asked Feb 28, 2014 by sreemathi.v

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Which of the following will undergo a connizzara reaction ?

asked Feb 28, 2014 by meena.p

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The correct sequence regarding basicity of following compounds are

asked Feb 28, 2014 by sreemathi.v

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In the reaction

asked Feb 28, 2014 by meena.p

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In the below reaction B is mainly

asked Feb 28, 2014 by sreemathi.v

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Which of the following reactions can be used to prepare the below one

asked Feb 28, 2014 by sreemathi.v

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