Class 12th

If a person is suffering from the deficiency of nor - adrenaline, what kind of drug can be suggested?

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Contributor-Level 10

Among its different uses noradrenaline is used as an anti-depressant.

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2 months ago

A diatomic molecule X₂ has a body centered cubic (bcc). The density of the molecule is 6.17 g cm⁻³. The number of molecules present in 200 g² of X₂ is: (Avogadro constant (NA) = 6 * 10²³ mol⁻¹)

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Contributor-Level 10

ρ = M/V
∴ 6.17 = (2 x MX? ) / (N? x (300 x 10? ¹? )³)
Solving MX? = 50 g
∴ No. of molecules in 200 g
= (200/50) x N? = 4 N?

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2 months ago

Class 12th Physics

A parallel plate capacitor whose capacitance C is 14 pF is charged by a battery to a potential difference V = 12V between its plates. The charging battery is now disconnected and a porcelain plate with k = 7 is inserted between the plates, then the plate would oscillate back and forth between the plates with a constant mechanical energy of . pJ. (Assume no friction)

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Contributor-Level 10

Initial charge Q = CV = 14 * 10? ¹² * 12 = 168 * 10? ¹² C

Initial energy U_in = ½ CV² = ½ (14 * 10? ¹²) * 12² = 1008 pJ

When the battery is disconnected and a dielectric (k=7) is inserted, the new capacitance is C' = kC.

The charge Q remains constant.

Final energy U_f = Q²/2C' = Q²/ (2kC) = (CV)²/ (2kC) = CV²/ (2k)

U_f = (14 * 10? ¹² * 12²) / (2 * 7) = 144 pJ

Mechanical energy available for oscillation

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Class 12th Atoms

If an electron is moving in the nth orbit of the hydrogen atom, then its velocity (v_n) for the nth orbit is given as :

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Class 12th Chemistry Chemical Kinetics

Contributor-Level 10

Velocity of an electron in the nth orbit:

v ∝ 1/n

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A flask contains a mixture of compounds A and B. Both compounds decompose by first - order kinetics. The half lives for A and B are 300 s and 180 s, respectively. If the concentrations of A and B are equal initially, the time required for the concentration of A to be four times that of B (in s) is: (Use ln 2 = 0.693 )

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For A
0.693/300 = (2.303/t) log (A? /A? )

For B
0.693/180 = (2.303/t) log (B? /B? )

Given A? = B? & A? = 4B?
Substituting & solving we get t = 900 s

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2 months ago

Class 12th Physics

An AC current is given by I = I₁sinωt + I₂cosωt. A hot wire ammeter will give a reading:

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Contributor-Level 10

I = I? sin (ωt) + I? cos (ωt)

This can be written as I = I? sin (ωt + φ), where I? = √ (I? ² + I? ²)

A hot wire ammeter reads the rms value of the current.

I_rms = I? /√2 = √ (I? ² + I? ²)/√2

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2 months ago

Which of the following is not an essential amino acid?

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2 months ago

Identify the correct molecular picture showing what happens at the critical micellar concentration (CMC) of an aqueous solution of a surfactant

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Class 12th Physics Moving Charges and Magnetism

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At CMC, the particles cluster together through lyophobic end to form associated colloid called micelle. Further all lyophilic ends (polar head) get projected towards water.

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2 months ago

A solenoid of 1000 turns per meter has a core with relative permeability 500. Insulated windings of the solenoid carry an electric current of 5 A. The magnetic flux density produced by the solenoid is: (permeability of free space = 4π*10^-7H/m)

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Contributor-Level 10

B = μni

B = (500 * 4π * 10? ) * 1000 * 5

B = π Tesla

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Class 12th Physics

The output of the given combination gates represents:

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