In a common emitter transistor amplifier current gain is 9 and resistance gain is 20. The voltage gain will be :

In hydrogen atom light corresponding to the transition \(n=4\) to \(n=2\) falls on cesium metal. The work function of the metal is 1.9 eV . What is the maximum kinetic energy of the photoelectrons emitted?

The forbidden energy gaps in conductors, semiconductors and insulators are \( (E_g)_c, (E_g)_s \) and \( (E_g)_I \) respectively. What is the relation among them ?

To obtain a n-type silicon semiconductor, it must be doped with

Some important general properties of the electric field lines are given below:
(A) Field lines start from positive charges and end at negative charges
(B) In a charge-free region, electric field lines can be taken to be continuous curves without any breaks
(C) Electrostatic field lines form closed loops
(D) Two field lines can never cross each other
Choose the correct answer from the options given below:

In a series LR circuit, the inductive reactance is equal to the resistance R of the circuit. An emf \( E = E_0 \cos \omega t \) is applied to the circuit. The average power dissipated in one cycle is :

A plane wave is incident on a concave mirror of radius R. The shape of the reflected wavefront will be

A 1.0 m long metallic rod is rotated with an angular frequency of \( 500 \, \text{rad s}^{-1} \) with one end hinged at the center and the other end at the circumference of a circular metallic ring of radius 1 m about an axis passing through the center and perpendicular to the plane of the ring. A constant and uniform magnetic field of 0.6 T parallel to the axis exists everywhere. The emf developed between the center and the ring is

Which of the following is a molecular solid?

The demand function (in Rs.) for a product is \(P=20-0.25 x\). where P is the price per unit and \(x\) is the number of units sold. Find the price of one unit when the revenue is maximized

Match List I with List - II.

List - I	List - II
(A) A community that is in near equilibrium with the environment	(I) Ecological succession
(B) The entire sequence of communities that successively change in a given area	(II) Xerarch succession
(C) A gradual and fairly predictable change in species composition of an area	(III) Climax community
(D) Succession of plants in dry areas	(IV) Sere(s)

Choose the correct answer from the options given below :

Phenol can be distinguished from ethanol by the following reagent :

Read the following passage carefully and answer the given questions.
The B-lymphocytes produce an army of proteins in response to pathogens. Each antibody molecule has four peptide chains, two small called light chains and two longer called heavy chains. Virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection. Symptoms of allergic reactions include sneezing, watery eyes, running nose and difficulty in breathing. The use of drugs like anti-histamine, adrenalin and steroids quickly reduce the symptoms of allergy.
Lymphoid organs are the organs where origin and/or maturation and proliferation of lymphocytes occur. The primary lymphoid organs are bone marrow and thymus. After maturation the lymphocytes migrate to secondary lymphoid organs like spleen, lymph nodes, tonsils, Peyer's patches of small intestine and appendix. Heroin commonly called smack is chemically diacetylmorphine which is a white, odourless, bitter crystalline compound. This is obtained by acetylation of morphine, which is extracted from the latex of poppy plant Papaver somniferum.
Which one of the following organs is not a secondary lymphoid organ in humans?