Recent questions in Physics

A convex lens is used in the experiment of conjugate focus method where image of the object is formed in the same place for two positions of the lens. The size of image in 1st position is $4\;cm$ and in the second position is $16 \;cm$ . The length of the object is

asked Mar 18, 2014 by meena.p

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In conversion of limestone to lime, $CaCO_3(s) \rightarrow CaO(s) + CO_2(g)$ the values of $\Delta H^{\circ}\: and\: \Delta S^{\circ}$ are 179 kJ/mol 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, temperature above which conversion of limestone to lime will be spontaneous is

asked Mar 18, 2014 by thanvigandhi_1

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Identify correct statement regarding spontaneous process

asked Mar 18, 2014 by thanvigandhi_1

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Assuming that water vapor is an ideal gas, the internal energy change ( $\Delta U$ ) when 1 mole of water is vaporized at 1 bar pressure and $100^{\circ}C$ (molar enthalpy of vaporization of water at 1 bar and 373 K = 41 kJ/mol and R = 8.314 J/Kmol) will be

asked Mar 18, 2014 by thanvigandhi_1

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In a potentiometer experiment it is found that no current flows through the galvanometer when balancing length is 52 cm of potentiometer when shant resistance of $5 \Omega$ is used balancing length becomes 40 cm The internal resistance of cell is

asked Mar 18, 2014 by meena.p

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Standard entropy of $X_2, Y_2\: and\: XY_3$ are 60, 40 and 50 J/Kmol respectively. For the reaction, $\large\frac{1}{2}$ $X_2 + Y_2 \rightarrow XY_3;\: \: \: \: \: \: \: \: \Delta H = -30\: kJ,$ to be at the equilibrium, the temperature will be

asked Mar 18, 2014 by thanvigandhi_1

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In an experiment to determine the Resistance of a coil it is found the volit meter values is $30.3\;V$ and ammeter reading is $0.020\;A$ least count of voltmeter is $0.1\;V$ and Least count of ammeter is $1\;mA$ . The value of R is

asked Mar 18, 2014 by meena.p

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A beam white light when passed through prism suffers dispersion. When light is passed through hollow prism it suffers.

asked Mar 18, 2014 by meena.p

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The characteristic curve for a zener diode is shown. The zener voltage is

asked Mar 18, 2014 by meena.p

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We use spherical pendulum bob because

asked Mar 18, 2014 by meena.p

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The percentage of uncertainty in measurement given as $55 \pm 2\;kg$ is approximately.

asked Mar 18, 2014 by meena.p

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A wire of length L and of cross sectional area A is fixed between rigid supported of negligible tension . If cooled the tension in the wire.

asked Mar 18, 2014 by meena.p

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In meter bridge apparatus the bridge wire possess

asked Mar 18, 2014 by meena.p

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In a vernier calliper if the vernier is on the right side of the zero of the main scale and nth vernier scale division coincides with main scale division correct reading is

asked Mar 18, 2014 by meena.p

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On the basis of the following thermo chemical data $[ \Delta G_f^{\circ} (H^+ )(aq) = 0]$ $H_2O(l) \rightarrow H^+ (aq) + OH^-(aq);\: \: \: \: \: \Delta H = 57.32\: kJ$ $H_2(g) + \large\frac{1}{2} (g) \rightarrow H_2O(l); \: \: \: \: \: \: \Delta H = -286\: kJ$ The value of enthalpy of formation of $OH^-\: ion$ at $25^{\circ}C$ is

asked Mar 17, 2014 by thanvigandhi_1

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The standard enthalpy of formation of $NH_3$ is $-46\: kJ/mol.$ If the enthalpy of formation of $H_2$ from its atoms is $-436\: kJ/mol$ and that of $N_2$ is $-712\: kJ/mol$ , the average bond enthalpy of $N-H$ bond in $NH_3$ is

asked Mar 17, 2014 by thanvigandhi_1

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Which of the following statements is true?

asked Mar 17, 2014 by thanvigandhi_1

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One mole of non-ideal gas undergoes a change of state $(2\: atm, 3.01\: L,\: 95K) \: to\: (4\: atm,\: 5L,\: 245K)$ with change in internal energy, $\Delta U = 30\: L-atm$ . The change in enthalpy of the process in $L-atm$ is

asked Mar 17, 2014 by thanvigandhi_1

1 answer

Starting with same initial conditions an ideal gas expands from volume $V_1$ to volume $V_2$ in three different paths. The work done by the gas is $W_1$ if process is purely isothermal, $W_2$ if process is purely isobaric and $W_3$ , if process is purely adiabatic. Which is correct?

asked Mar 17, 2014 by thanvigandhi_1

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Heat of combustion of $CH_4(g), \: C(graphite),\: H_2(g)$ are -20 kcal, -40 kcal and -10 kcal respectively. The heat of formation of methane is

asked Mar 17, 2014 by thanvigandhi_1

1 answer

Given that, $NH_3 + 3Cl_2(g) \rightarrow NCl_3(g) + 3HCl(g);\: \: \: \: \Delta H_1 = -x_1$ $N_2(g) + 3H_2(g) \rightarrow 2NH_3(g);\: \: \: \: \: \: \: \: \Delta H_2 = -x_2$ $H_2(g) + Cl_2(g) \rightarrow 2HCl(g);\: \: \: \: \: \: \: \: \Delta H_3 = x_3$ The heat of formation of $NCl_3(g)$ from the above data is

asked Mar 17, 2014 by thanvigandhi_1

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A travelling microscope consisting of a compound microscope which slides along a graduated vertical pillar attached to a horizontal base.The main scale is divided into half a millimeter and vernier scale of the microscope is divided into 50 divisions equivalent to 49 main scale division. The least count is

asked Mar 17, 2014 by sreemathi.v

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1 mole of ideal gas is allowed to expand isothermally from the initial volume of 1L to 10L, the value of $\Delta U$ for the process is $(R = 2\: cal/Kmol)$

asked Mar 17, 2014 by thanvigandhi_1

1 answer

Given that $C+O_2 \rightarrow CO_2;\: \: \: \: \: \Delta H^{\circ} = -x\: kJ\: and\: 2CO+O_2 \rightarrow 2CO_2; \: \: \: \: \:\Delta H^{\circ} = -y\: kJ$ The standard enthalpy of formation of carbon monoxide is

asked Mar 17, 2014 by thanvigandhi_1

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Calculate Q for isothermal reversible expansion of one mole of ideal gas from initial pressure of 1 bar to 0.1 bar at a constant temperature of 273 K.

asked Mar 17, 2014 by thanvigandhi_1

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Calculate the value of equilibrium constant for a reaction at 400K $2NOCl(g)2NO(g) + Cl(g)$ $\Delta S$ and $\Delta H$ are 122 J/Kmol and 77.2 kJ/mol respectively.

asked Mar 17, 2014 by thanvigandhi_1

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If an antenna radiates electromagnetic wave from a height of h the range of coverage d is given by where R is radius of earth

asked Mar 17, 2014 by sreemathi.v

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The polymerization of ethylene to linear polyethylene is represented by the reaction $nCH_2=CH_2 \rightarrow (CH_2-CH_2)_n$ where $n$ has a large integral value. Given that $\Delta H_{C=C}$ and $\Delta H_{C-C}$ at 298 K are 590 and 331 kJ/mol. Calculate the enthalpy of polymerization per mol of ethylene.

asked Mar 17, 2014 by thanvigandhi_1

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Which of the following statements are correct?

asked Mar 17, 2014 by sreemathi.v

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In which of the following conditions, is work done on the gas?

asked Mar 17, 2014 by thanvigandhi_1

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In amplitude modulation

asked Mar 17, 2014 by sreemathi.v

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Attenuation is

asked Mar 17, 2014 by sreemathi.v

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Surface wave propagation is done near the surface of earth.Surface wave propagation is sutable upto

asked Mar 17, 2014 by sreemathi.v

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Optical fibres use for transmission the principle of

asked Mar 17, 2014 by sreemathi.v

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For commercial FM transmission maximum frequency deviation allowed

asked Mar 17, 2014 by sreemathi.v

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What is the modulating index of an FM carrier having carrier signal swing of 60KHz and modulating signal frequency of 2KHz

asked Mar 17, 2014 by sreemathi.v

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What is the modulating factor given maximum peak to peak voltage of an AM is 10mv and minimum peak to peak voltage is 2mv.

asked Mar 17, 2014 by sreemathi.v

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A 1KHz modulating voltage is supplied to a FM(frequency modulator) produces a frquency deviation of 1.2KHz.The modulating index is

asked Mar 17, 2014 by sreemathi.v

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Amplitude of carrier wave is 20v amplitude of signal is 2v.Percentage of modulation is

asked Mar 17, 2014 by sreemathi.v

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What type of data does optical fibres carry

asked Mar 17, 2014 by sreemathi.v

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When microwave signals propagate along the curvature of the earth,the effect is called

asked Mar 17, 2014 by sreemathi.v

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An FM signal has deviation 75KHz and the highest frequency of modulation is 15KHz.Band width is

asked Mar 17, 2014 by sreemathi.v

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An oscillator is producing a FM wave of frequency 1KHz with a variation of 5KHz.What is modulating index.

asked Mar 17, 2014 by sreemathi.v

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An FM signal has a frequency of 105MHz and highest frequency acquired is 105.05MHz when modulated by a signal.The carrier swing is

asked Mar 17, 2014 by sreemathi.v

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Power of carrier wave is 1000Watt.What is the required power of the signal to modulate it 100%

asked Mar 17, 2014 by sreemathi.v

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An amplitude modulated wave has 800watt of total power content.For 100% modulation the carrier should have power content equal to

asked Mar 17, 2014 by sreemathi.v

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If level of modulation is increased ________ power is increased

asked Mar 17, 2014 by sreemathi.v

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An audio signal given by $20\sin(2\pi \times 4000t)$ is used for modulating carrier wave given by $40\sin (2\pi\times 400000t)$ .The frequency spectrum of modulated wave

asked Mar 17, 2014 by sreemathi.v

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An audio signal $20\sin(2\pi\times 400t)$ is used to modulating a carrier wave given by $40\sin(2\pi\times 40000t)$ .The percentage modulation is

asked Mar 17, 2014 by sreemathi.v

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In AM transmission power of carrier wave is 50KW what will be the transmission power if the modulation is 80%

asked Mar 17, 2014 by sreemathi.v

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