Class 12th

Contributor-Level 10

P? + 3NaOH + 3H? O → PH? + 3NaH? PO? (A)
Here, NaH? PO? is a reducing agent.
NaH? PO? + AgNO? + H? O → Ag + HNO? + NaH? PO?
Equivalents of NaH? PO? = equivalents of Ag (n-factor of NaH? PO? = 4)
1 mole * 4 = n moles of Ag * 1
So, moles of Ag = 4.

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2 months ago

Two cells of emf 2E and E with internal resistance r? and r? respectively are connected in series to an external resistor R (see figure). The value of R, at which the potential difference across the terminals of the first cell becomes zero is:

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Class 12th Chemistry Chemical Kinetics

Contributor-Level 10

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2 months ago

For a certain first order reaction 32% of the reactant is left after 570s. The rate constant of this reaction is _______ *10⁻³ s⁻¹. (Round off to the nearest integer).
[Given: log₁₀2 = 0.301, ln10 = 2.303]

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Contributor-Level 10

Kt = 2.303 log? (A? /A? )
K * 570 = 2.303 log? (100/32)
K = [2.303 / 570] [log?10² - log?2? ]
K = [2.303 / 570] [2 - 5 * 0.301] = [2.303 / 570] * 0.495 = 0.002 = 2.0 * 10? ³ s? ¹
Ans = 2

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2 months ago

A carrier signal C(t) = 25 sin(2.512 * 10¹⁰t) is amplitude modulated by a message signal m(t) = 5 sin(1.57 * 10⁸t) and transmitted through an antenna. What will be the bandwidth of the modulated signal?

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Class 12th Physics Ncert Solutions Class 12th

Contributor-Level 10

Frequency of message signal, f? = (1.57 * 10? ) / (2 * 3.14) = 2.5 * 10? Hz
Bandwidth = 2f? = 5 * 10? Hz = 50MHz

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2 months ago

Your friend is having eye sight problem. She is not able to see clearly a distant uniform window mesh and it appears to her non-uniform and distorted. The doctor diagnosed the problems as:

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Raj Pandey

Contributor-Level 9

An eye with defect of myopia can not see distant objects clearly, while that of astigmatism sees objects non-uniform and distorted.

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2 months ago

A hairpin like shape as shown in figure is made by bending a long current carrying wire. What is the magnitude of a magnetic field at point P which lies on the centre of the semicircle?

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Contributor-Level 10

The magnetic field B is calculated as:
B = 2 * (μ? I / 4πr) + (μ? I / 4πr) = (μ? I / 4πr) * (2 + π)

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2 months ago

Two identical photo-cathodes receive the light of frequencies f? and f? respectively. If the velocities of the photo-electrons coming out are v? and v? respectively, then

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Contributor-Level 10

The equation representing the photoelectric effect is given as:
(1/2)mv? ² = hf? - φ . (1)

This continues the solution from number 6 on the previous page.
(1/2)mv? ² = hf? - φ . (2)
With the help of equations (1) and (2), we can write:
v? ² - v? ² = (2h/m) (f? - f? )

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2 months ago

Class 12th Chemistry

The point of intersection and sudden increase in the slope, in the diagram given below, respectively, indicates:

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Contributor-Level 10

At the point of intersection in an Ellingham diagram? G for two processes becomes equal, so? G for the reduction becomes zero. A sudden increase in the slope indicates a change in the state of the metal oxide, i.e., from solid to liquid or liquid to vapor.

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2 months ago

What happens to the inductive reactance and the current in a purely inductive circuit if the frequency is halved?

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Contributor-Level 10

Given the initial relationships:
X? = ωL and i? = V? / (ωL)
If the angular frequency ω is halved, the inductive reactance X? is halved, while the peak current i? is doubled.

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2 months ago

Class 12th Chemistry

Which of the following reaction is an example of ammonolysis?

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