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Recent questions tagged physics
Questions
A carrier wave is modulated to 75%.If the power of carrier wave is 500W what is power of modulated wave
jeemain
physics
communication-systems
ch15
class12
medium
modulation
asked
Mar 17, 2014
by
sreemathi.v
1
answer
An audio frequency of $4\times 10^3$Hz is used to modulate a carrier wave of frequency 1MHz.The band width is
jeemain
physics
communication-systems
ch15
class12
medium
modulation
asked
Mar 17, 2014
by
sreemathi.v
1
answer
A amplitude modulated wave has maximum amplitude of 700mV and minimum amplitude of 200mV.Calculate the modulation factor
jeemain
physics
communication-systems
ch15
class12
medium
modulation
asked
Mar 17, 2014
by
sreemathi.v
1
answer
A TV tower has a height of 100m.If the coverage range is to be made three times then by how much should the height of the tower be increased.
jeemain
physics
communication-systems
ch15
class12
medium
propagation-of-electromagnetic-waves
asked
Mar 17, 2014
by
sreemathi.v
1
answer
Calculate the standard entropy change for a reaction $XY$ if the value of $ \Delta H^{\circ} = 28.4 \: kJ$ and equilibrium constant is $1.8 \times 10^{-7}\: at\: 298\: K$.
jeemain
physics
thermodynamics
cbse
class11
class12
q45
medium
asked
Mar 16, 2014
by
thanvigandhi_1
1
answer
Calculate the standard free energy change for the following reaction \[\] $Zn(s) + Cu^{2+} (aq) \rightarrow Cu(s) + Zn^{2+} (aq)$ \[\] Given that $ \Delta G_f^{\circ}\: for \: Cu^{2+} (aq)\: and \: Zn^{2+} (aq)$ as 65 kJ/mol and -147.2 kJ/mol respectively.
jeemain
physics
thermodynamics
cbse
class11
class12
q44
medium
asked
Mar 16, 2014
by
thanvigandhi_1
1
answer
For the reaction $N_2(g) + 3H_2(g)\rightarrow 2NH_3(g) \Delta H = -95.4 \: kJ\: and\: \Delta S = -198.3\: J/K$ \[\] Calculate the temperature at which free energy change is equal to zero.
jeemain
physics
thermodynamics
cbse
class11
class12
q43
medium
asked
Mar 16, 2014
by
thanvigandhi_1
1
answer
Calculate the entropy change when 36 g of liquid water evaporates at $373\: K( \Delta H_{vap} = 40.63\: kJ/mol)$
sat
chemistry
chemical-reactions-and-thermochemistry
jeemain
physics
thermodynamics
cbse
class11
class12
q42
medium
asked
Mar 16, 2014
by
thanvigandhi_1
1
answer
Calculate the entropy change for the conversion of 1 gm of ice to water at 273 K and one atm pressure. The enthalpy of fusion of ice is 6.025 kJ/mol
jeemain
physics
thermodynamics
cbse
class11
class12
q41
medium
asked
Mar 16, 2014
by
thanvigandhi_1
1
answer
Calculate the bond energy of $Cl-Cl$ bond from the following data: \[\] $CH_4(g) + Cl_2(g) \rightarrow CH_3Cl(g) + HCl(g); \Delta H = -100.3\: kJ$. Also the bond energies of $C-H,\: C-Cl,\: H-Cl$ bonds are 413, 326 and 431 kJ/mol respectively.
jeemain
physics
thermodynamics
cbse
class11
class12
q40
medium
asked
Mar 16, 2014
by
thanvigandhi_1
1
answer
Calculate the enthalpy change ($ \Delta H$) of the following reaction: \[\] $2C_2H_2(g) + 5O_2(g) \rightarrow 4CO_2(g) + 2H_2O(g)$ given average bond energies of various bonds, i.e, $C-H,\: CC,\: O=O,\: C=O,\: O-H$ as 414, 814, 499, 724 and 640 kJ/mol respectively.
jeemain
physics
thermodynamics
cbse
class11
class12
q39
medium
asked
Mar 16, 2014
by
thanvigandhi_1
1
answer
Calculate standard internal energy change($ \Delta E^{\circ}$) for the reaction \[\] $OF2(g) + H_2O(g) \rightarrow O_2(g) + 2HF(g)$ \[\] Given standard enthalpies of formation $ \Delta H_f^{\circ}\: of\: OF_2(g), H_2O(g)\: and\: HF(g)$ are23, -241.8 and -268.6 kJ/mol respectively.
jeemain
physics
thermodynamics
cbse
class11
class12
q38
medium
asked
Mar 16, 2014
by
thanvigandhi_1
1
answer
2.5 mol of ideal gas at 2 atm and $27^{\circ}C$ expands isothermally to 2.5 times of its original volume against the external pressure of 1 atm. Calculate q
jeemain
physics
thermodynamics
cbse
class11
class12
q37
medium
asked
Mar 16, 2014
by
thanvigandhi_1
1
answer
1 mole of ideal monatomic gas at $ 27^{\circ}C$ expands adiabatically against a constant external pressure of $1.5\: atm$ from a volume of $4\: dm^3\: to\: 16\: dm^3$ . Calculate $ \Delta E$.
jeemain
physics
thermodynamics
cbse
class11
class12
q36
medium
asked
Mar 16, 2014
by
thanvigandhi_1
1
answer
A gas cylinder of $5L$ capacity containing $4\; kg$ of He gas at $27^{\circ}C$ developed leakage leading to the escape of the gas into atmosphere. If atmospheric pressure is $1 \;atm$, calculate the work done by the gas assuming ideal behavior.
jeemain
physics
thermodynamics
cbse
class11
class12
q35
medium
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
A sample of gas is compressed by an average pressure of $0.5\: atm$ so as to decrease its volume from $400 \: cm^3$ to $200\: cm^3$ . During the process $8\: J$ of heat flows out to surroundings. Calculate the change in internal energy of the system
jeemain
physics
thermodynamics
cbse
class11
class12
q34
medium
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
An ideal monoatomic gas at temperature $27^{\circ}C$ and pressure $10^6N/m^2$ cal of heat is added to the system without changing the volume. Calculate the final temperature of the gas. $(R = 8.31 \: J/mol-K \: and\: J = 4.18 \: J/cal)$
jeemain
physics
thermodynamics
cbse
class11
class12
q33
medium
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
At 1 atmospheric pressure, 1 gm of water having a volume of $1\: cm^3$ becomes $1.091\: cm^3$ of ice on freezing. The heat of fusion of water at 1 atmosphere is 80 cal/g. What is the change in internal energy during the process?
jeemain
physics
thermodynamics
cbse
class11
class12
q32
medium
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
Two moles of a diatomic ideal gas is taken through the process $PT$ = const. Its temperature is increased from $T_oK$ to $2T_oK$. Find the work done by the system.
jeemain
physics
thermodynamics
cbse
class11
class12
q31
medium
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
The bond energy of $O-H$ bond is $109\: kcal/mol$. The value of $ \Delta H_f$ of $H2_O(g)$ is
jeemain
physics
thermodynamics
cbse
class11
class12
q30
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
Which of the following substance has zero value of $ \Delta G_f^{\circ} $?
jeemain
physics
thermodynamics
cbse
class11
class12
q29
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
Which of the following process is endothermic?
jeemain
physics
thermodynamics
cbse
class11
class12
q28
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
The standard enthalpies of formation of $NO_2(g)\: and\: N_2O_4(g)$ are $8$ and $2\: kcal/mol$ respectively. The heat of dimerisation of $ NO_2$ in gaseous state is
jeemain
physics
thermodynamics
cbse
class11
class12
q26
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
The enthalpy of formation of $ Cl(g)\: is\: x\: kJ/mol$. The value of $ \Delta H_{Cl-Cl} $ will be
jeemain
physics
thermodynamics
cbse
class11
class12
q26
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
Which of the following is not a state property?
jeemain
physics
thermodynamics
cbse
class11
class12
q25
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
If a system absorbs reversibly 600 J of heat and performs 250 J of work, the increase in internal energy of the system is
jeemain
physics
thermodynamics
cbse
class11
class12
q24
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
The energy change of the reaction \[\] $C_2H_6(g) \rightarrow 2C(g) + 6H(g)$ \[\] is $x\: kJ$. The bond energy of $C-H$ bond is
jeemain
physics
thermodynamics
cbse
class11
class12
q23
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
For a natural process in any isolated system
jeemain
physics
thermodynamics
cbse
class11
class12
q22
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
What is correct about the expression -$ P \Delta V$?
jeemain
physics
thermodynamics
cbse
class11
class12
q21
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
“The entropy of a perfect crystal at absolute zero is zero”. The statement corresponds to which law of thermodynamics
jeemain
physics
thermodynamics
cbse
class11
class12
q20
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
A process is spontaneous at all temperatures, if
jeemain
physics
thermodynamics
cbse
class11
class12
q19
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
For which of the following process, $ \Delta S_{total} \: is\: < 0$,
jeemain
physics
thermodynamics
cbse
class11
class12
q18
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
For a reversible process at equilibrium, the entropy change $ \Delta S$ is given by
jeemain
physics
thermodynamics
cbse
class11
class12
q17
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
Which of the following is zero during adiabatic expansion of gas?
jeemain
physics
thermodynamics
cbse
class11
class12
q16
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
The absolute entropy of a free element
jeemain
physics
thermodynamics
cbse
class11
class12
q15
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
A minus sign of the free energy change denotes that
jeemain
physics
thermodynamics
cbse
class11
class12
q14
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
Which of the following relations is not correct?
jeemain
physics
thermodynamics
cbse
class11
class12
q13
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
Which of the following is not spontaneous?
jeemain
physics
thermodynamics
cbse
class11
class12
q12
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
When a solid melts, there is
jeemain
physics
thermodynamics
cbse
class11
class12
q11
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
For an exothermic reaction, which of the following is always $ < 0$
jeemain
physics
thermodynamics
cbse
class11
class12
q10
easy
asked
Mar 15, 2014
by
thanvigandhi_1
1
answer
A circuit is made as shown --- The circuit contains a component made of bimetallic strip . If the temperature is increased , will the bulb glow ? ( Assume the emf of battery is enough to light the bulb )
jeemain
physics
class11
cbse
thermodynamics
difficult
asked
Mar 15, 2014
by
yamini.v
1
answer
If two rods of length L and 2L having coefficients of linear expansion $\;\alpha\;$ & $\;2 \alpha\;$ respectively are connected such that length becomes 3L ,The average coefficient of linear expansion of the composite rod equals ---
jeemain
physics
class11
cbse
thermodynamics
difficult
asked
Mar 15, 2014
by
yamini.v
1
answer
Rods of equal length & equal cross - section are arranged as shown - The thermal conductivity of the rods are written correspondingly . The equivalent thermal conductivity of the system is -
jeemain
physics
class11
cbse
thermodynamics
difficult
asked
Mar 15, 2014
by
yamini.v
1
answer
Figure shows the arrangement , gas is thermally insulated . Having pressure $\;p_{g}\;$ ( greater than atmospheric pressure $\;p_{a}\;$ ) . Spring of force constant k is initially unstretched . Position of mass m & area S is friction less and in equilibrium position , it rises up a distance $\;x_{0}\;$ , then -
jeemain
physics
class11
cbse
thermodynamics
difficult
asked
Mar 15, 2014
by
yamini.v
1
answer
2 Rods of length l and 2l , Area 2A and A are joined end to end . Now by hammering we change the area of rod from 2A to A . Find moment of inertia about the joint in final condition . It is given that both the rods have some density$\;\rho$
jeemain
physics
class11
cbse
medium
rotational
motion
moment-of-inertia
asked
Mar 15, 2014
by
yamini.v
1
answer
$30\; gm$ ice at $\;-20^{0}C\;$ is mixed with $20\; gm$ water at $\;90^{0}C\;$. Find the final composition and temperature of mixture . (Latent Heat of fusion $80\; cal /gm$ )
jeemain
physics
class11
cbse
thermodynamics
easy
asked
Mar 15, 2014
by
yamini.v
1
answer
A beam of electrons travels at $3 \times 10^{6} m/s$ through a uniform magnetic field of $4 \times 10^{-2} T$ at right angles to the field, as shown in the figure. How strong is the force acting on each electron?
jeemain
physics
moving-charge-and-magnetism
magnetic-field-in-the-axis-of
current-in-a-circular-loop
easy
asked
Mar 14, 2014
by
balaji.thirumalai
1
answer
Suppose a magnet is suspended by a vertical string, attached to its middle point. Given that the horizontal component of earth's magnetic field is $25\;\mu T$ and the vertical component of of earth's magnetic field is $40\;\mu T$, find the position in which the magnet can stay in equilibrium.
jeemain
physics
class12
ch5
magnetism-and-matter
earths-magnetism
easy
asked
Mar 14, 2014
by
balaji.thirumalai
1
answer
Find the magnetic field at point P in the figure below, where I = 15 A and R = 20 cm.
jeemain
physics
class12
ch4
moving-charge-and-magnetism
magnetic-field-on-axis-current-circular-loop
medium
asked
Mar 14, 2014
by
balaji.thirumalai
1
answer
A solenoid is 2.7-m long, has a radius of 0.85 cm, and has 600 turns. It carries a current I of 2.5 A. What is the magnitude of the magnetic field B inside the solenoid and far from either end?
jeemain
physics
class12
ch4
moving-charge-and-magnetism
magnetic-field
solenoid-and-toroid
medium
asked
Mar 14, 2014
by
balaji.thirumalai
1
answer
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