Which of the following frequencies will be suitable for beyond-the-horizon communication using sky waves?

Which of the following phenomenon is responsible for the reddish appearance of sun during sunset or sunrise ?

Match List I with List II

LIST I	LIST II
A. Photodiode	I. junction area is kept much larger and biasing not required
B. Light emitting diode	II. used to detect intensity of radiation
C. Solar cell	III. Used as a voltage regulator
D. Zener diode	IV. emits spontaneous radiation under forward bias

Choose the correct answer from the options given below:

A current of 2 A is maintained in a long straight conductor placed in air. Calculate the magnitude of the magnetic field at a distance of 2 m from the conductor.

A radioactive isotope has a half life of T years. How long (in years)will it take the activity to reduce to 3.125% of it's original value?

A parallel plate capacitor half filled with a dielectric of dielectric constant 4 has a capacitance of 10 \( \mu\text{F} \). The capacitance without the dielectric is :

If the radii of curvature of the faces of a double convex lens are 10 cm and 15 cm, respectively and its refractive index is 1.5, the focal length of the lens in air is

The integral \(\int \frac{x^4+2}{x^2+1} d x\) is equal to

Read the passage carefully and answer the questions.
Electrochemistry is the study involving two types of processes. One type involves the production of electricity from the energy released during a spontaneous chemical reaction. Galvanic cells like Daniel cells are used to produce electricity from the redox reaction. Nernst equation of a galvanic cell gives the relation between the standard cell potential and the concentration of the species involved in the redox reaction. The second type of study involves the cells in which electrical energy is used to bring about the chemical reactions in a non-spontaneous process. The conductance of electrolytic solution depends on many factors including the nature of the electrolyte and the dimensions of the electrolytic cell.
When KCl is dissolved in water, the Potassium ion is;

Three charges Q, +2q and +2q are placed at the vertices of an equilateral triangle. If the net electrostatic potential energy of the system is zero, then Q is equal to

The maximum value of \(\left(\frac{1}{x}\right)^x\) for \(x>0\) is

In order to link the alien DNA, the vector needs to have very few, preferably single, recognition sites for the commonly used restriction enzymes. Presence of more than one recognition sites within the vector will generate several fragments, which will complicate the gene cloning. In Biolistics or gene gun method cells are bombarded with high velocity micro particles of gold or tungsten coated with DNA. The ligation of alien DNA is carried out at a restriction site present in one of the two antibiotic resistance genes. For example, you can ligate a foreign DNA at the BamH I site of tetracycline resistance gene in the vector pBR322. Since the DNA is enclosed within the membranes, we have to break the cell open to release DNA along with other macromolecules such as RNA, proteins, polysaccharides and also lipids. The RNA can be removed by treatment with ribonuclease whereas proteins can be removed by treatment with protease. Other molecules can be removed by appropriate treatments and purified DNA ultimately precipitates out after the addition of chilled ethanol.
Which one of the following statements is correct with reference to biolistics?

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Carbohydrates such as cane sugar, glucose, starch etc. belong to a class of naturally occurring organic compounds. Structurally these are polyhydroxy aldehydes or ketones or the compounds which produce such units on hydrolysis. Carbohydrates which are sweet in taste are called sugars. Theses sugars can be reducing or non-reducing. Monosaccharides cannot be hydrolyzed to simpler units whereas Oligosaccharides yield two to ten monosaccharide units on hydrolysis. Polysaccharides yield large number of monosaccharide units on hydrolysis. This class of biomolecules is essential for living systems as they serve as storage molecules in plants and animals. In addition, they provide raw materials for important industries like furniture, textiles, paper, lacquers and breweries. Two aldopentose form important constituents of nucleic acids. Carbohydrates are also called saccharides (Greek: sakcharon which means sugar). Sugar which is used in household and in milk also comes under this class of biomolecules.
Reducing sugars respond to