Identify the correct statements in the following:
(A) Optical fibres consist of a core and cladding
(B) Optical fibres are fabricated such that light reflected at one side of the inner surface strikes the other at an angle smaller than the critical angle.
(C) Optical fibres make use of the phenomenon of total internal reflection.
(D) Optical fibres can be used as an optical pipe
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The mass number of helium is 4 and that of sulphur is 32. How many times the radius of sulphur nucleus is bigger than that of helium ?

Which of the following statements are correct?
A. The process of generation of conduction electrons and holes and process of recombination is a simultaneous process.
B. To increase the conductivity of a semiconductor manifold, a few parts per million of a suitable impurity is added.
C. Extrinsic semiconductors doped with trivalent impurity are called n-type semi conductors.
D. During the formation of a p-n junction, two processes diffusion and drift occurs.
E. The thickness of depletion region is of the order of a millimeter.
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At the time of sunset the sun appears to be at an altitude higher than its actual position. This is because of

What would be the amount of energy released if 1 g of a substance is converted to energy? (Given, speed of light in vacuum \(=3 \times 10^8 m s ^{-1}\) )

A transmitting antenna at the top of a tower has a height 18 m and the height of the receiving antenna is 32 m. What is the maximum distance between them for satisfactory communication in line-of-sight mode? Given radius of earth is \( 6.4 \times 10^6 \text{ m} \)

A TV tower has a height of 20 m and the radius of earth is \(6.4 \times 10^6 m\). The range of the tower is:

Arrange the following ducts pertaining to male reproductive system starting from seminiferous tubules
(A) Vas deferens
(B) Vasa efferentia
(C) Rete testis
(D) Epididymis
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Nearly all the transition elements display typical metallic properties such as high tensile strength, ductility, malleability, high thermal and electrical conductivity and metallic lustre. The transition metals (with the exception of Zn, Cd and Hg) are very hard and have low volatility. Their melting and boiling points are high. They have high enthalpies of atomization. lons of the same charge in a given series show progressive decrease in radius with increasing atomic number. However, the variation within a series is quite small. The filling of 4f before 5d orbital results in a regular decrease in atomic radii called Lanthanoid contraction which essentially compensates for the expected increase in atomic size with increasing atomic number. The net result of the lanthanoid contraction is that the second and the third d series exhibit similar radii (e.g., Zr 160 pm, Hf 159 pm) and have very similar physical and chemical properties. There is an increase in ionisation enthalpy along each series of the transition elements from left to right. The first ionisation enthalpy, in general, increases, but the magnitude of the increase in the second and third ionisation enthalpies for the successive elements, is much higher along a series. One of the notable features of a transition elements is the great variety of oxidation states these may show in their compounds.
Atomic number of \(\mathrm{V}, \mathrm{Mn}, \mathrm{Cu}\) and Zn is \(23,25,29\) and 30 respectively. Which of them shows a positive value for the standard electrode potential \(E^{\circ}\left(M^{2+} / M\right)\) ?

Which of the following does not have direct role in genetic engineering?

Which of the following combination should be selected for better tuning of an LCR circuit used for communication ?

0.04 F of charge will liberate how much of oxygen gas (at STP) from acidified water?

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The coordination compounds are of great importance. These compounds are widely present in the mineral, plants and animal world and are known to play many important functions in the area of analytical chemistry, metallurgy, biological systems, industry and medicine. For example, coordination compounds find use in many qualitative and quantitative chemical analysis. Some important metal extraction and purification make use of complex formation. Hardness of water can be estimated by stable complex formation of Ca\(^{2+}\) and Mg\(^{2+}\)
Impure nickel is converted to which of its complex to be decomposed to yield pure nickel?