Two batteries of emf 5 V with internal resistance 2 \( \Omega \) and 6 V with internal resistance 3 \( \Omega \) are connected in series with an external resistor. If the current in the circuit is 0.5 A, then the resistance of the resistor is

igure given below shows variation of photocurrent with anode potential for different intensities of incident radiation. Some of the results obtained from the experiments are described below on the basis of the graph. Identify the correct results:

(A) The photoelectric current is higher for higher intensity of the incident radiation.
(B) The negative potential required to decrease the photocurrent at different intensities to zero is different.
(C) If the positive potential of the anode is increased beyond a certain value, the photocurrent does not increase for a given intensity.
(D) If the potential applied at the anode is zero, then the photocurrent is lower than the maximum value of current for the given intensity.
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The hydrogen atom is excited from ground state to a state with the principal quantum number (n) = 4. The number of spectral lines in the emission spectra will be

A wire carries a current of 10 A in south to north direction. The magnetic field due to 1 cm piece of wire at a point 200 cm northeast from the piece :

What is the mathematical expression for potential gradient?

Which of the following is the wrong statement? Coulomb's law describes the electric force that

A heater coil is rated 100 W, 200 V. It is cut into two identical parts. Both parts are connected together in parallel to the same source of 200 V. The energy liberated per second in the new combination is:

These structures represent which particular kind of halides :

A vertical electric field of magnitude \( 4.9 \times 10^5 \text{ NC}^{-1} \) just prevents a water droplet of mass \( 0.1 \text{ g} \) from falling. What is the charge on the droplet? Take acceleration due to gravity \( 9.8 \text{ ms}^{-2} \).

The magnetic susceptibility of the material of a rod is 499. Permeability of vacuum is \( 4\pi \times 10^{-7} \text{ H/m} \). The absolute permeability of the material of the rod is:

Match List-I with List-II

List-I  (Geological periods)	List-II (Plant forms)
(A) Cretaceous	(I) Seed ferns
(B) Jurassic	(II) Progymnosperms
(C) Carboniferous	(III) Sphenopsids
(D) Devonian	(IV) Conifers

Choose the correct answer from the options given below:

Match List I with List II

LIST - I (compound)	LIST - II (Hybridization & Geometry)
A. \(X e F_6\)	I. \(sp^3d^3 \text{ distorted octahedral}\)
B. \(XeO _3\)	II. \(sp^3d^2 \text{ square planar}\)
C. \(X e O F_4\)	III. \(sp^3\text{ pyramidal }\)
D. \(X e F_4\)	IV. \(sp^3d^2 \text{ square pyramidal}\)

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RNA interference involves silencing of a specific mRNA due to complementarity of