The minimum energy required to excite a Hydrogen atom from its ground state is :

A chain reaction in fission of uranium is possible because

At a place, the vertical component of Earth's magnetic field is \(\sqrt{3}\) times its horizontal component. If the total intensity of Earth's magnetic field at the place is 0.4 G, then the horizontal component of Earth's magnetic field is:

Two plane monochromatic waves propagating in the same direction with amplitudes \( 3A \) and \( 5A \) and differing in phase by \( \frac{2\pi}{3} \), superimpose. The amplitude of the resulting wave is :

A polythene bag rubbed with a woollen jersey is found to have a negative charge of \( 3 \times 10^{-7} \text{ C} \). The number of electrons transferred from woollen jersey to the polythene would be :

List I contains physical quantities related to mechanical oscillations of a block of mass m attached to spring of force constant k. List II contains physical quantities related to a LC oscillator. Match List I with List II.

List I	List II
(A) Mass m	(I) Charge q
(B) Force Constant k	(II) Inductance L
(C) Displacement x	(III) Reciprocal capacitance 1/C
(D) Velocity ( \(v=\frac{d x}{d t}\) )	(IV) Current \(\left(i=\frac{d q}{d t}\right)\)

On the basis of analogies between mechanical and electrical quantities;
Choose the correct answer from the options given below:

A short bar magnet of magnetic moment \(m =0.45 J / T\) is placed in a uniform magnetic field of 0.22 T . If the bar is free to rotate in the plane of the field, what is the potential energy of the magnet in stable and unstable equilibrium respectively?

Match List-l with List-II

LIST- I (Population interaction)	LIST- II ( Example)
(A) Parasitism	(I) Herbivores and plants
(B) Commensalism	(II) Human liver fluke
(C) Mutualism	(III) Egret and grazing cattle
(D) Competition	(IV) Lichens

Choose the correct answer from the options given below:

Recombinant DNA technology involves the following steps in a specific sequence.
(A) Culture of the host cell
(B) Extraction of desired product
(C) Isolation of desired DNA fragments
(D) Transformation of the recombinant DNA into the host cell Arrange these sequences correctly and choose the correct answer from the options given below:

The sickle cell anaemia is a

Select the hormone which is not secreted by human placenta:

Area of the region bounded by the curve \(y=\cos (x)\) and x -axis between \(x=0\) and \(x=\pi\) is :

Microbes in human welfare Microbes are a very important component of life on earth. we use microbes and microbially derived products almost every day, like LAB to make curd, yeast to make bread, adding flavor and texture to cheese, producing antibiotics etc. The addition of LAB, improves the milk quality by increasing vit. B12. Cheese is one of the oldest food items in which microbes are used. For example, large holes in Swiss cheese are due to CO2 produced by the bacterium Propionibacterium sharmanii. The BOD test measures the rate of uptake of oxygen by microorganisms in a sample of water and thus, indirectly, BOD is a measure of the organic matter present in the water. The greater the BOD of waste water, the more is its polluting potential. In anaerobic sludge digesters, bacteria produce a mixture of gases like methane, hydrogen sulphide and carbon dioxide. These gases form biogas and can be used as a source of energy. Biofertilisers are organisms that enrich the nutrient quality of the soil. The main sources of biofertilisers are bacteria, fungi and cyanobacteria. You have studied about the nodules on the roots of leguminous plants formed by the symbiotic association of Rhizobium. These bacteria fix atmospheric nitrogen into organic forms, which is used by the plant as a nutrient. Other bacteria can fix atmospheric nitrogen while free-living in the soil (examples Azospirillum and Azotobacter).
The large holes in Swiss cheese are generated by-