The magnetic dipole moment associated with an atom due to orbital motion of an electron in fourth stationary orbit of the hydrogen atom is :

A proton and an alpha particle moving with equal kinetic energies enter perpendicularly into a magnetic field. If \( r_p \) and \( r_\alpha \) are the respective radii of their circular paths, what will be the ratio \( \frac{r_p}{r_\alpha} \)?

The ratio of lengths of two wires is 2 : 3 and the ratio of their resistivities is 3 : 2. If they have the same resistance then the ratio of their respective diameters is

The correct relation(s) among total energy, kinetic energy and potential energy as per Bohr's theory of hydrogen atom is/are
(A) T.E. \(=-\) K.E.
(B) K.E. \(=\) P.E.
(C) K.E. \(=-\frac{\text { P.E. }}{2}\)
(D) T.E. \(=\frac{\text { P.E. }}{2}\)
(E) T.E. \(=\) P.E.
Choose the correct answer from the options given below :

Identify the correct statements among the following.
(A) The number of electrons (\( n_e \)) is more than the number of holes (\( n_h \)) in intrinsic conductors.
(B) Semiconductors are elements (Si, Ge) type as well as compounds (GaAs, CdS).
(C) The number of charge carriers can be changed by 'doping' of a suitable impurity in pure semiconductors.
(D) Holes are essentially electron vacancies in a valence band.
Choose the correct answer from the options given below:

Two coherent light beams of intensities I and 4 I are superimposed. The maximum and minimum possible intensities in the resulting pattern are :

Identify the correct statements among the following:
(A) An electromagnetic wave travels in vacuum like sound waves.
(B) An ultraviolet wave is not an electromagnetic wave.
(C) An electromagnetic wave can travel from earth to the planet, saturn.
(D) An electromagnetic wave may have less velocity in a medium than in vacuum.
Choose the correct answer from the options given below:

Electromagnetic wave carries

The set of positive integers less than 50 forming the equivalence class of 6 modulo 9 is given by :

Which one of the following diagnostic techniques is based on the principle of antigen-antibody interaction?

In Young's double slit experiment, the width of the fringes obtained with light of wavelength 6000 \( \text{\AA} \) is 3.0 mm. If the entire apparatus is immersed in a liquid medium of refractive index 1.50, then the fringe width would be

The relative magnetic permeability of diamagnetic substances is always:

Read the passage carefully and answer the questions based on the passage:
Pest Resistance Plants
Various nematodes parasitize a wide variety of plants and animals, including human beings. A nematode, Meloidogyne incognitia, infects the roots of tobacco plants and causes a great reduction in yield. A noval strategy was adopted to prevent this infestation which was based on the process of RNA interference (RNAi). RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing). Plants, bacteria, fungi and animals whose genes have been altered by manipulation are called Genetically Modified Organisms (GMO). GM plants have been useful in many ways. Genetic modification has: (i) made crops more tolerant to abiotic stresses (cold, drought, salt, heat). (ii) reduced reliance on chemical pesticides (pest-resistant crops). (iii) helped to reduce post harvest losses. (iv) increased efficiency of mineral usage by plants (this prevents early exhaustion of fertility of soil). (v) enhanced nutritional value of food, e.g., golden rice, i.e., Vitamin 'A' enriched rice. Genetic modification of organisms can have unpredicatable results when such organisms are introduced into the ecosystem. Therefore, the Indian Government has set up organisations such as GEAC (Genetic Engineering Approval Committee), which will make decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services. Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).
Bacillus thuringiensis produces proteins that do not kill certain insects such as