What is the total energy of electron in the \( n^{th} \) stationary orbit of hydrogen atom ?

The electric field amplitude of an electromagnetic wave is \(100 N C ^{-1}\) and its frequency is 50 MHz . What is the magnitude of wave vector \(k\), (given speed of electromagnetic wave is \(3 \times 10^8 m s ^{-1}\) )

The two possible nuclei to complete the reactions given below are, respectively
(1) \({ }_7 N^{14}+{ }_2 He ^4={ }_8 O ^{17}+\)_______
(2) \({ }_8 O ^{16}+{ }_1 H ^2={ }_7 N^{14}+\)_____

Four point charges -2Q, +q, -2q and +Q are placed at four corners of a square A, B, C and D, respectively, as shown in the figure and OA = OB = \( a/\sqrt{2} \). If the potential at the center of a square is zero, what is the relation between Q and q?

The expression of the magnetic energy stored in a solenoid in terms of magnetic field B, cross-sectional area A and length l of the solenoid, is:

To increase the current sensitivity of a moving coil galvanometer by 75%, its resistance is increased so that the new resistance becomes twice its initial resistance. By what factor does its voltage sensitivity change ?

Choose the correct statements:
(A) The angle of incidence corresponding to an angle of refraction \(90^{\circ}\) is called critical angle (i).
(B) Refractive index of denser medium \(\mu=\frac{1}{\sin \left(i_c\right)}\).
(C) For \(i>i_c\), Snell's law of refraction cannot be satisfied.
(D) The refractive index of air increases with decrease in density.
(E) Rainbow is the combined effect of dispersion, refraction and reflection of sunlight by droplets.
Choose the correct answer from the options given below :

A screen is placed at a distance of 90 cm from an object. The image of the object on the screen is formed by a convex lens placed at two different locations separated by 20 cm. The focal length of the lens is approximately

The vector equation of the line joining the points \((-2,-3,-4)\) and \((1,-2,4)\) is :

Read the following passage carefully and answer the given questions.
Insulin consists of two short polypeptide chains- chain A and chain B, that are linked together by disulphide bridges. Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans, coleopterans and dipterans. Bt toxin protein is converted into an active form of toxin due to the alkaline pH of the gut which solubilise the crystals. Transgenic animals that produce useful biological products can be created by the introduction of the portion of DNA (or genes) which codes for a particular product such as human protein (alpha-1-antitrypsin) used to treat emphysema. 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. (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.
Which one of the followings is not true about insulin?

In flowering plants, zygote develops into :

Why must the reacting molecules have a minimum energy for an effective collision?

Match List-l with List-II

List-l (Test)	List-II (Identification)
(A) Hinsberg's Test	(I) Primary, Secondary and tertiary Amines
(B) Isocyanide test	(II) Aliphatic and Aromatic primary amines
(C) Azo dye test	(III) Primary Aromatic amines
(D) Tollen's Test	(IV) Reducing sugars

Choose the correct answer from the options given below: