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Answers posted by mosymeow_1

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Which of the following properties are of lyophilic colloids?
answered Apr 4, 2014
Answer: do not show Tyndall effectLyophilic colloids do not show Tyndall effect since the particles ...
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Micelles are what type of colloids?
answered Apr 4, 2014
Answer: AssociatedMicelles are the cluster/aggregated particles formed by association of colloids in...
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Which of the following are not the properties of colloidal solution?
answered Apr 4, 2014
Answer: Unstable natureA colloidal solution is a type of a mixture which consists of particles whose...
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Which of the following reactions shows the formation of positively / negatively charged sol correctly?
answered Mar 18, 2014
Answer: $FeCl_3 + H_2O(excess) \longrightarrow Fe_2O_3.xH_2O | Fe^{3+}$If ferric chloride is added t...
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Which of the following diagram shows the situation of the $As_2S_3$ particles after electrophoresis?
answered Mar 18, 2014
Answer: The particles of $As_2S_3$ are negatively charged and they move towards oppositely charged e...
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Which of the following explains the process of de-emulsification?
answered Mar 18, 2014
Answer: process of decomposing an emulsion back into its constituent liquids.De-emulsification is th...
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Which among the following is a non-elastic gel?
answered Mar 18, 2014
Answer: silica gelSilica gel is rigid and does not have the property of elasticity. It changes into ...
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Which of the following below is used as an eye lotion?
answered Mar 18, 2014
Answer: ArgyrolColloidal sol of silver is called argyrol and is used as eye lotion.
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Fertile soils are also colloidal in nature. Which of the following acts as a protective colloid in soil?
answered Mar 18, 2014
Answer: HumusIn the soil, the humus acts as a protective colloid. Because of the colloidal nature, s...
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Which of the following states the reason behind the formation of 'Tail of Comets' phenomenon in a colloidal solution?
answered Mar 17, 2014
Answer: Tyndall effectTail behind a comet is seen as Tyndall cone due to scattering of light by the ...
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The coagulating power of an electrolyte for arsenious sulphide sol decreases in the order:
answered Mar 17, 2014
Answer: $Al^{3+} > Ba^{2+} > Na^+$$As_2S_3$ ia a negative sol and therefore coagulating power ...
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STEM stands for
answered Mar 17, 2014
Answer: both Scanning Transmission Electron Microscope & Scanning Tunneling Electron Microscope....
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The colour of a colloidal solution depends upon
answered Mar 17, 2014
Toolbox:Colour of a colloidal solution depends upon particles size and also the direction in which i...
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A colloidal solution of gold in water is
answered Mar 17, 2014
Toolbox:Colour of a colloidal solution depends upon the particle size.Answer: all the threeColour of...
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The average particle mass in colloidal solutions can be determined by
answered Mar 17, 2014
Toolbox:The only measurable colligative property of colloidal solution is osmotic pressure.Answer: o...
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The CMC of a given soap in water is $10^{-3}$ mol/L. A $10^{-4}$ mol/L solution of this soap in water is a
answered Mar 17, 2014
Answer: true solutionAs the concentration of soap ($10^{-4} mol/L$) is less than its CMC value ($10^...
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Gold numbers of protective colloids A, B, C and D are 0.50, 0.01, 0.05 and 0.005 respectively. The correct order of their protective powers is
answered Mar 17, 2014
Toolbox:Smaller the gold number, greater is the protective power.Answer: A < C < B < DSmall...
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Langmuir adsorption isotherm is deduced using the assumption.
answered Mar 17, 2014
Answer: The adsorption sites are equivalent in their ability to adsorb the particles.Langmuir adsorp...
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The reactions given below, are the catalyst and corresponding process / reaction are matched, the mismatch is
answered Mar 17, 2014
Answer: $N_2O_5$ : Haber Bosch processHaber Bosch process is used for the synthesis of ammonia. The ...
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A plot of $\log \;\dfrac{x}{m}$ versus $\log\; p$ for the adsorption of a gas on a solid gives a straight line with slope equal to
answered Mar 17, 2014
Answer: 1/nFor the adsorption of a gas on a solid $\frac{x}{m} = kp^{1/n}$ This equation is known as...
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The number of moles of lead nitrate needed to coagulate 2 mol of colloidal $[AgI]I^-$ is
answered Mar 17, 2014
Answer: 1$2[AgI]I^- + Pb^{2+} \longrightarrow PbI_2 + 2AgI$Thus, 2 moles of $[AgI]I^-$ are coagulate...
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Which among the following statements are correct with respect to adsorption of gases on a solid?
answered Mar 17, 2014
Toolbox:According to Freundlich isotherm, $\frac{x}{m} = kp^{1/n}$According to Langmuir isotherm, $\...
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The coagulation of 200 mL of a positive colloid took place when 0.73 g HCl was added to it without changing the volume much. The flocculation value of HCl for the colloid is
answered Mar 17, 2014
Answer: 100200 mL of the sol needs = $\large\frac{0.73}{36.5 g/mol}$ = 0.02 mol = 20 m mol1000 mL of...
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What is the equation form of langmuir isotherm under high pressure?
answered Mar 17, 2014
Toolbox:According to Langmuir isotherm $\frac{x}{m} = \frac{ap}{(1+bp)}$Answer: $\frac{x}{m} = \frac...
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Which of the following is used to produce smoke screens?
answered Mar 17, 2014
Answer: Calcium phosphide$Ca_3P_2 + 6H_2O \longrightarrow 3Ca(OH)_2 + 2PH_3$Phosphene ($PH_3$) so fo...
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Which of the following molecule is most suitable to disperse benzene in water?
answered Mar 16, 2014
Answer: Benzene (an oily substance) and water will form an emulsion in the presence of a micelle for...
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Which of the following forms micelles in aqueous solution, above certain concentration?
answered Mar 16, 2014
Answer: Dodecyl trimethyl ammonium chlorideDodecyl trimethyl ammonium chloride $[C_{12}H_{25}N^+(CH_...
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The volume of a colloidal particle, $V_c$ as compared to the volume of a solute particle, $V_s$ in a true solution could be
answered Mar 16, 2014
Answer: $\frac{V_c}{V_s} \approx 10^{3}$For a true solution, the diameter range is 1 to < 10 $\ov...
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In Zeigler-Natta polymerisation of ethylene the active species is
answered Mar 16, 2014
Answer: $Ti^{3+}$$Ti^{3+}$ species from $TiCl_3$ compound having active site vacant which accomodat...
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Milk can be preserved by adding a few drops of
answered Mar 16, 2014
Answer: Formaldehyde solutionFormaldehyde kills the micro-organisms which spoils the milk by produci...
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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
answered Feb 28, 2014
Answer: 1118 K$\Delta G^\circ = \Delta H^\circ - T \Delta S^\circ$Since, $\Delta H^\circ$ is +ve and...
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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
answered Feb 28, 2014
Answer: +60 eV$\Delta S(A\rightarrow C)= S_C-S_A=50eV$$\Delta S(C\rightarrow B)=S_D-S_C=30eV$$\Delta...
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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?
answered Feb 28, 2014
Answer: -208.1 kJ/molEnthalpy of hydrogentaion of cyclohexene = -119.5 kJ/mol$\therefore$ calculated...
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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 $JK^{-1}mol^{-1}$)
answered Feb 28, 2014
Answer: 1238.78 J/mol$C(s) + 1/2 O_2 (g) \longrightarrow CO(g)$$\Delta n_g = 1-\frac{1}{2} = \frac{1...
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Given, standard enthalpy of formation $(\Delta _f H^\circ)$ at 298 k for methane is -74.8 kJ/mol. What other information is required to determine the average energy for C-H bond formation would be
answered Feb 28, 2014
Answer: The dissociation energy of $H_2$ and enthalpy of sublimation of carbonGiven $C(graphite) + 2...
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One mole of monoatomic ideal gas at T (K) is expanded from 1 L to 2 L adiabitcally under constant external pressure of 1 atm. The final temperature of gas in kelvin is
answered Feb 28, 2014
Answer: T - $\frac{2}{3\times 0.0821}$Here $P_{ext} = 1 atm$$V_1$ = 1 L and $V_2$ = 2 LR = 0.0821 L ...
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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?
answered Feb 28, 2014
Answer: 400 K$\Delta H$ = 30 kJ/mol = 30,000 J/mol$\Delta S$ = 75 $Jmol^{-1}K^{-1}$At boiling point,...
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Which of the following reactions will define $\Delta H^\circ _f$?
answered Feb 28, 2014
Answer: $\frac{1}{2}H_2(g) + \frac{1}{2}F_2(g) \rightarrow HF(g)$Standard enthalpy of formation is e...
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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
answered Feb 28, 2014
Answer: -121 kJ/mol$C_6H_{12} + 9 O_2 \rightarrow 6CO_2 + 6H_2O$ ; $\Delta H_1= -3920$ kJ/mol$C_6H_{...
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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?
answered Feb 28, 2014
Answer: 44.0$H=U+PV$$\Rightarrow \Delta H = \Delta U + \Delta PV$$\Rightarrow \Delta H = \Delta U + ...
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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?
answered Feb 28, 2014
Answer: 100 $Jmol^{-1}K^{-1}$ Liquid water $\rightarrow $ steam$\Delta G^{\circ} = \Delta H^\circ - ...
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Which of the following gas has the highest heat of combustion?
answered Feb 28, 2014
Answer: EthaneGas with highest number of C atoms and having all single bond should have highest valu...
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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
answered Feb 28, 2014
Answer: PositiveThe reaction is endothermic, so on getting energy, forward reaction is favoured prod...
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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?
answered Feb 28, 2014
Answer: It can be made spontaneous by decreasing the pressure at 298 K.For the reaction to be sponta...
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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).
answered Feb 28, 2014
Answer: 239.6 $JK^{-1}mol^{-1}$$\Delta S^\circ _f[CH_3OH(l)] = \frac{\Delta H^\circ _f - \Delta ^\ci...
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Devitrification of glass is a process for which change in entropy, $\Delta S$ is
answered Feb 28, 2014
Answer: -veDevitrification of glass is the onset of crystallisation in a super cooled liquid. The pr...
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Dissolution of gases in water is
answered Feb 28, 2014
Answer: always an exothermic processDissolution of gases in water is a spontaneous process. As such ...
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Two coins eash weighing 10 g are heated to 473 K and dropped into two identical vessels A and B, each containing 500 g of water at 298 K. The coin dropped in vessel A is made up of aluminium and the coin dropped into vessel B is amde up of silver. The rise in temperature of water in container
answered Feb 27, 2014
Answer: A will be more than BAtomic mass of Al(27) is less than the atomic mass of Ag(108). As both ...
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At $298\; K, 0.1\; mol$ of methane is burnt in a bomb calorimeter such that $\Delta V=0$. The heat so produced is taken up by a large amount of water so that $\Delta T$ is very small.
answered Feb 27, 2014
Answer: $\Delta H < \Delta E$At 298 K, $CH_4(g) + 2O_2(g) \rightarrow CO_2(g) + 2H_2O(l)$$\Delta ...
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A $1.0\; g$ sample of substance A at $100^\circ C$ is added to $100\; mL$ of $H_2O$ at $25^\circ C$. Using separate $100\; mL$ portions of $H_2O$, the procedure is repeated with substance $B$ and then with substance $C$. How will the final temperatures of the water compare?
answered Feb 27, 2014
Answer: $T_A>T_B>T_C$Heat evolved or absorbed, $Q=ms\Delta t$Where,m= mass of the substance,s ...
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