List of top Questions asked in UP Board XII

Match the vitamins given in Column (I) with the diseases caused by their deficiency in Column (II):
Column (I): A) Vitamin A, B) Vitamin B1, C) Vitamin C, D) Vitamin K, E) Vitamin B12.
Column (II): a) Increase in clotting time of blood, b) Night blindness, c) Beri-beri, d) Pernicious anaemia, e) Scurvy.
Which test is used to differentiate between primary, secondary and tertiary amines?
Transition metals, with a few exceptions, are extremely hard and less volatile. Explain.
Which of the following is an aldehyde?
Which of the following is not a transition metal?
What is the coordination number of Co in the complex \( K_3[Co(C_2O_4)_3] \)?
Which formula is used to calculate osmotic pressure?

Option 1: Write down the definition of electric dipole moment. Derive the formula for the electric field intensity at an axial point of an electric dipole.
OR
Option 2: In the given combination of capacitors (connected across a 22 V supply), find out (i) the total capacitance, (ii) the charge on the 4 \( \mu\text{F} \) capacitor and (iii) the total stored energy. The network contains capacitors of 4 \( \mu\text{F} \), 2 \( \mu\text{F} \), 1 \( \mu\text{F} \), 2 \( \mu\text{F} \), 1 \( \mu\text{F} \) and 12 \( \mu\text{F} \).
Derive the formula \(\dfrac{n}{v}-\dfrac{1}{u}=\dfrac{n-1}{R}\) due to refraction of light on a spherical surface.
OR
Draw a circuit diagram of p-n junction full wave rectifier and describe its working. Also, give the graphical representation of input and output current.
Option 1: Depict the series and the parallel combination of cells. When is the series and when is the parallel combination suitable? A cell of e.m.f. \( E \) and internal resistance \( r \) is connected with an external resistance \( R \). Draw a graph between the voltage \( V \) across \( R \) and the current \( i \) flowing in it.
OR
Option 2: State Ampere's circuital law and, on its basis, find the formula for the magnetic field produced at a point due to an infinitely long straight current-carrying wire. A current of \( 10^{-4}\ \text{A} \) flows in a rectangular coil of dimensions \( 1.0\ \text{cm} \times 1.5\ \text{cm} \). The plane of the coil is parallel to a magnetic field of \( 0.6\ \text{N/A m} \). The coil has 30 turns. Calculate the torque acting on the coil.
L, C and R are connected in series with an alternating current source. When there will be resonance in the circuit? What will be the nature of impedance during resonance?
OR
State the Faraday's laws of electromagnetic induction. Define self induction, state the Lenz's law regarding direction of self induced current. In a coil, due to change of current at the rate of 1 A/s an e.m.f. of 1 V is produced. What will be the coefficient of self inductance of the coil?
Define current density \( (\vec{J}) \) and write its unit. Prove that \( \vec{J} = \sigma\vec{E} \), where \( \sigma \) is the specific conductivity (conductivity) of the conductor and \( \vec{E} \) the electric field inside the conductor.
State the important characteristics of electromagnetic waves.
How can a galvanometer be converted into a voltmeter? Explain with the help of a circuit diagram.
Option 1: Write the 'lens maker' formula for a thin lens. The refractive index of the material of a thin lens is \( n \) and its focal length is \( f \). The lens is placed in a medium of refractive index \( n \). Find the focal length of the lens in the medium.
OR
Option 2: What is the difference between unpolarized and polarized light? Two polaroids A and B are placed such that light polarized by A cannot pass through B. Can some light be obtained by using a third polaroid?
What are matter waves? Write the de-Broglie formula for matter waves. The de-Broglie wavelength for a photon and an electron are same. Which will have greater energy?

What is the need of doping of intrinsic semiconductors? Ideal diodes are used in the given circuits. Find the value of current in both the circuits.
Write down the difference between displacement current and conduction current. The equation of an electromagnetic wave is \(B_y = 2\times10^{-7}\,\sin(500x + 1.5\times10^{11}t)\) Tesla. Find the equation of the electric field of the wave, the direction of propagation and the wavelength of the wave.
Find the formula for the couple acting on a magnetic dipole placed in a magnetic field. On its basis, define magnetic dipole moment.

Give formula for power loss in an alternating circuit. Find the e.m.f. of source in the circuit and the phase difference between resultant potential and the current flowing in the circuit. (Series R-L-C driven by an AC source with \(V_R=40\) V across the resistor, \(V_L=50\) V across the inductor and \(V_C=20\) V across the capacitor.)
What are isotone nuclei? In a nucleus average mass of nucleons is \(1.67\times10^{-27}\) Kg. Find the density of nucleus. [Given \(R_0 = 1.2\times10^{-15}\) m.]
Explain the meaning of the electrical capacity of a conductor. How capacity of a conductor can be increased?

An atom makes a transition on receiving energy from an external source, as shown in the figure. Depict the lines of possible spectrum and calculate the wavelength of any two spectral lines. (Energy levels: \(n=1\) at 0, \(n=2\) at 4.86 eV, \(n=3\) at 6.67 eV, \(n=4\) at 8.80 eV.)
State Gauss' law in electrostatics. Charge inside a Gaussian surface is zero. Comment on the electric field intensity at each point of the surface.
Explain the meaning of work function of a photosensitive surface.