In which of the following cases an atom is expected to possess nuclear magnetic moment? ?->(Show Answer!)

1. In which of the following cases an atom is expected to possess nuclear magnetic moment?

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MCQ-> In a modern computer, electronic and magnetic storage technologies play complementary roles. Electronic memory chips are fast but volatile (their contents are lost when the computer is unplugged). Magnetic tapes and hard disks are slower, but have the advantage that they are non-volatile, so that they can be used to store software and documents even when the power is off.In laboratories around the world, however, researchers are hoping to achieve the best of both worlds. They are trying to build magnetic memory chips that could be used in place of today’s electronics. These magnetic memories would be nonvolatile; but they would also he faster, would consume less power, and would be able to stand up to hazardous environments more easily. Such chips would have obvious applications in storage cards for digital cameras and music- players; they would enable handheld and laptop computers to boot up more quickly and to operate for longer; they would allow desktop computers to run faster; they would doubtless have military and space-faring advantages too. But although the theory behind them looks solid, there are tricky practical problems and need to be overcome.Two different approaches, based on different magnetic phenomena, are being pursued. The first, being investigated by Gary Prinz and his colleagues at the Naval Research Laboratory (NRL) in Washington, D.c), exploits the fact that the electrical resistance of some materials changes in the presence of magnetic field— a phenomenon known as magneto- resistance. For some multi-layered materials this effect is particularly powerful and is, accordingly, called “giant” magneto-resistance (GMR). Since 1997, the exploitation of GMR has made cheap multi-gigabyte hard disks commonplace. The magnetic orientations of the magnetised spots on the surface of a spinning disk are detected by measuring the changes they induce in the resistance of a tiny sensor. This technique is so sensitive that it means the spots can be made smaller and packed closer together than was previously possible, thus increasing the capacity and reducing the size and cost of a disk drive. Dr. Prinz and his colleagues are now exploiting the same phenomenon on the surface of memory chips, rather spinning disks. In a conventional memory chip, each binary digit (bit) of data is represented using a capacitor-reservoir of electrical charge that is either empty or fill -to represent a zero or a one. In the NRL’s magnetic design, by contrast, each bit is stored in a magnetic element in the form of a vertical pillar of magnetisable material. A matrix of wires passing above and below the elements allows each to be magnetised, either clockwise or anti-clockwise, to represent zero or one. Another set of wires allows current to pass through any particular element. By measuring an element’s resistance you can determine its magnetic orientation, and hence whether it is storing a zero or a one. Since the elements retain their magnetic orientation even when the power is off, the result is non-volatile memory. Unlike the elements of an electronic memory, a magnetic memory’s elements are not easily disrupted by radiation. And compared with electronic memories, whose capacitors need constant topping up, magnetic memories are simpler and consume less power. The NRL researchers plan to commercialise their device through a company called Non-V olatile Electronics, which recently began work on the necessary processing and fabrication techniques. But it will be some years before the first chips roll off the production line.Most attention in the field in focused on an alternative approach based on magnetic tunnel-junctions (MTJs), which are being investigated by researchers at chipmakers such as IBM, Motorola, Siemens and Hewlett-Packard. IBM’s research team, led by Stuart Parkin, has already created a 500-element working prototype that operates at 20 times the speed of conventional memory chips and consumes 1% of the power. Each element consists of a sandwich of two layers of magnetisable material separated by a barrier of aluminium oxide just four or five atoms thick. The polarisation of lower magnetisable layer is fixed in one direction, but that of the upper layer can be set (again, by passing a current through a matrix of control wires) either to the left or to the right, to store a zero or a one. The polarisations of the two layers are then either the same or opposite directions.Although the aluminum-oxide barrier is an electrical insulator, it is so thin that electrons are able to jump across it via a quantum-mechanical effect called tunnelling. It turns out that such tunnelling is easier when the two magnetic layers are polarised in the same direction than when they are polarised in opposite directions. So, by measuring the current that flows through the sandwich, it is possible to determine the alignment of the topmost layer, and hence whether it is storing a zero or a one.To build a full-scale memory chip based on MTJs is, however, no easy matter. According to Paulo Freitas, an expert on chip manufacturing at the Technical University of Lisbon, magnetic memory elements will have to become far smaller and more reliable than current prototypes if they are to compete with electronic memory. At the same time, they will have to be sensitive enough to respond when the appropriate wires in the control matrix are switched on, but not so sensitive that they respond when a neighbouring elements is changed. Despite these difficulties, the general consensus is that MTJs are the more promising ideas. Dr. Parkin says his group evaluated the GMR approach and decided not to pursue it, despite the fact that IBM pioneered GMR in hard disks. Dr. Prinz, however, contends that his plan will eventually offer higher storage densities and lower production costs.Not content with shaking up the multi-billion-dollar market for computer memory, some researchers have even more ambitious plans for magnetic computing. In a paper published last month in Science, Russell Cowburn and Mark Well and of Cambridge University outlined research that could form the basis of a magnetic microprocessor — a chip capable of manipulating (rather than merely storing) information magnetically. In place of conducting wires, a magnetic processor would have rows of magnetic dots, each of which could be polarised in one of two directions. Individual bits of information would travel down the rows as magnetic pulses, changing the orientation of the dots as they went. Dr. Cowbum and Dr. Welland have demonstrated how a logic gate (the basic element of a microprocessor) could work in such a scheme. In their experiment, they fed a signal in at one end of the chain of dots and used a second signal to control whether it propagated along the chain.It is, admittedly, a long way from a single logic gate to a full microprocessor, but this was true also when the transistor was first invented. Dr. Cowburn, who is now searching for backers to help commercialise the technology, says he believes it will be at least ten years before the first magnetic microprocessor is constructed. But other researchers in the field agree that such a chip, is the next logical step. Dr. Prinz says that once magnetic memory is sorted out “the target is to go after the logic circuits.” Whether all-magnetic computers will ever be able to compete with other contenders that are jostling to knock electronics off its perch — such as optical, biological and quantum computing — remains to be seen. Dr. Cowburn suggests that the future lies with hybrid machines that use different technologies. But computing with magnetism evidently has an attraction all its own.In developing magnetic memory chips to replace the electronic ones, two alternative research paths are being pursued. These are approaches based on:
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MCQ-> The membrane-bound nucleus is the most prominent feature of the eukaryotic cell. Schleiden and Schwann, when setting forth the cell doctrine in the 1830s, considered that it had a central role in growth and development. Their belief has been fully supported even though they had only vague notions as to what that role might be, and how the role was to be expressed in some cellular action. The membraneless nuclear area of the prokaryotic cell, with its tangle of fine threads, is now known to play a similar role.Some cells, like the sieve tubes of vascular plants and the red blood cells of mammals, do not possess nuclei during the greater part of their existence, although they had nuclei when in a less differentiated state. Such cells can no longer divide and their life span is limited Other cells are regularly multinucleate. Some, like the cells of striated muscles or the latex vessels of higher plants, become so through cell fusion. Some, like the unicellular protozoan paramecium, are normally binucleate, one of the nuclei serving as a source of hereditary information for the next generation, the other governing the day-to-day metabolic activities of the cell. Still other organisms, such as some fungi, are multinucleate because cross walls, dividing the mycelium into specific cells, are absent or irregularly present. The uninucleate situation, however, is typical for the vast majority of cells, and it would appear that this is the most efficient and most economical manner of partitioning living substance into manageable units. This point of view is given credence not only by the prevalence of uninucleate cells, but because for each kind of cell there is a ratio maintained between the volume of the nucleus and that of the cytoplasm. If we think of the nucleus as the control centre of the cell, this would suggest that for a given kind of cell performing a given kind of work, one nucleus can ‘take care of’ a specific volume of cytoplasm and keep it in functioning order. In terms of material and energy, this must mean providing the kind of information needed to keep flow of materials and energy moving at the correct rate and in the proper channels. With the multitude of enzymes in the cell, materials and energy can of course be channelled in a multitude of ways; it is the function of some information molecules to make channels of use more preferred than others at any given time. How this regulatory control is exercised is not entirely clear.The nucleus is generally a rounded body. In plant cells, however, where the centre of the cell is often occupied by a large vacuole, the nucleus may be pushed against the cell wall, causing it to assume a lens shape. In some white blood cells, such as polymorphonucleated leukocytes, and in cells of the spinning gland of some insects and spiders, the nucleus is very much lobed The reason for this is not clear, but it may relate to the fact that for a given volume of nucleus, a lobate form provides a much greater surface area for nuclear-cytoplasmic exchanges, possibly affecting both the rate and the amount of metabolic reactions. The nucleus, whatever its shape, is segregated from the cytoplasm by a double membrane, the nuclear envelope, with the two membranes separated from each other by a perinuclear space of varying width. The envelope is absent only during the time of cell division, and then just for a brief period The outer membrane is often continuous with the membranes of the endoplasmic reticulum, a possible retention of an earlier relationship, since the envelope, at least in part, is formed at the end cell division by coalescing fragments of the endoplasmic reticulum. The cytoplasmic side of the nucleus is frequently coated with ribosomes, another fact that stresses the similarity and relation of the nuclear envelope to the endoplasmic reticulum. The inner membrane seems to posses a crystalline layer where it abuts the nucleoplasm, but its function remains to be determined.Everything that passes between the cytoplasm and the nucleus in the eukaryotic cell must transverse the nuclear envelope. This includes some fairly large molecules as well as bodies such as ribosomes, which measure about 25 mm in diameter. Some passageway is, therefore, obviously necessary since there is no indication of dissolution of the nuclear envelope in order to make such movement possible. The nuclear pores appear to be reasonable candidates for such passageways. In plant cells these are irregularly, rather sparsely distributed over the surface of the nucleus, but in the amphibian oocyte, for example, the pores are numerous, regularly arranged, and octagonal and are formed by the fusion of the outer and inner membrane.Which of the following kinds of cells never have a nuclei?
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MCQ->In which of the following cases an atom is expected to possess nuclear magnetic moment?....

MCQ->Assertion (A): The angular momentum of an atom is due to three contributions viz. orbital, electron spin and nuclear spin.Reason (R): The nuclear spin magnetic moment is much more than electron spin magnetic moment.

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MCQ-> Read the following passage carefully and answer the questions given at the end. When Ratan Tata moved the Supreme Court, claiming his right to privacy had been violated, he called Harish Salve. The choice was not surprising. The former solicitor general had been topping the legal charts ever since he scripted a surprising win for Mukesh Ambani against his brother Anil. That dispute set the gold standard for legal fees. On Mukesh’s side were Salve, Rohinton Nariman, and Abhishek Manu Singhvi. The younger brother had an equally formidable line-up led by Ram Jethmalani and Mukul Rohatgi.The dispute dated back three-and-a-half years to when Anil filed case against his brother for reneging on an agreement to supply 28 million cubic metres of gas per day from its Krishna-Godavari basin fields at a rate of $ 2.34 for 17 years. The average legal fee was Rs. 25 lakh for a full day's appearance, not to mention the overnight stays at Mumbai's five-star suites, business class travel, and on occasion, use of the private jet. Little wonder though that Salve agreed to take on Tata’s case pro bono. He could afford philanthropy with one of India’s wealthiest tycoons.The lawyers’ fees alone, at a conservative estimate, must have cost the Ambanis at least Rs. 15 crore each. Both the brothers had booked their legal teams in the same hotel, first the Oberoi and, after the 26/ ll Mumbai attacks, the Trident. lt’s not the essentials as much as the frills that raise eyebrows. The veteran Jethmalani is surprisingly the most modest in his fees since he does not charge rates according to the strength of the client's purse. But as the crises have multiplied, lawyers‘fees have exploded.The 50 court hearings in the Haldia Petrochemicals vs. the West Bengal Government cost the former a total of Rs. 25 crore in lawyer fees and the 20 hearings in the Bombay Mill Case, which dragged on for three years, cost the mill owners almost Rs. 10 crore. Large corporate firms, which engage star counsels on behalf of the client, also need to know their quirks. For instance, Salve will only accept the first brief. He will never be the second counsel in a case. Some lawyers prefer to be paid partly in cash but the best are content with cheques. Some expect the client not to blink while picking up a dinner tab of Rs. 1.75 lakh at a Chennai five star. A lawyer is known to carry his home linen and curtains with him while travelling on work. A firm may even have to pick up a hot Vertu phone of the moment or a Jaeger-LeCoutre watch of the hour to keep a lawyer in good humour.Some are even paid to not appear at all for the other side - Aryama Sundaram was retained by Anil Ambani in the gas feud but he did not fight the case. Or take Raytheon when it was fighting the Jindals. Raytheon had paid seven top lawyers a retainer fee of Rs. 2.5 lakh each just to ensure that the Jindals would not be able to make a proper case on a taxation issue. They miscalculated when a star lawyer fought the case at the last minute. “I don’t take negative retainers”, shrugs Rohatgi, former additional solicitor general. “A Lawyer’s job is to appear for any client that comes to him. lt’s not for the lawyers to judge if a client is good or bad but the court”. Indeed. He is, after all, the lawyer who argued so famously in court that B. Ramalinga Raju did not ‘fudge any account in the Satyam Case. All he did was “window dressing”.Some high profile cases have continued for years, providing a steady source of income, from the Scindia succession battle which dates to 1989, to the JetLite Sahara battle now in taxation arbitration to the BCCI which is currently in litigation with Lalit Modi, Rajasthan Royals and Kings XI Punjab.Think of the large law firms as the big Hollywood studios and the senior counsel as the superstar. There are a few familiar faces to be found in most of the big ticket cases, whether it is the Ambani gas case, Vodafone taxation or Bombay Mills case. Explains Salve, “There is a reason why we have more than one senior advocate on a case. When you're arguing, he’s reading the court. He picks up a point or a vibe that you may have missed.” Says Rajan Karanjawala, whose firm has prepared the briefs for cases ranging from the Tata's recent right to privacy case to Karisma Kapoor’s divorce, “The four jewels in the crown today are Salve, Rohatgi, Rohinton Nariman and Singhvi. They have replaced the old guard of Fali Nariman, Soli Sorabjee, Ashok Desai and K.K. Venugopal.” He adds, “The one person who defies the generational gap is Jethmalani who was India's leading criminal lawyer in the 1960s and is so today.”The demand for superstar lawyers has far outstripped the supply. So a one-man show by, say, Rohatgi can run up billings of Rs. 40 crore, the same as a mid-sized corporate law firm like Titus and Co that employs 28 juniors. The big law filik such as AZB or Amarchand & Mangaldas or Luthra & Luthra have to do all the groundwork for the counsel, from humouring the clerk to ensure the A-lister turns up on the hearing day to sourcing appropriate foreign judgments in emerging areas such as environmental and patent laws. “We are partners in this. There are so few lawyers and so many matters,” points out Diljeet Titus.As the trust between individuals has broken down, governments have questioned corporates and corporates are questioning each other, and an array of new issues has come up. The courts have become stronger. “The lawyer,” says Sundaram, with the flourish that has seen him pick up many Dhurandhares and Senakas at pricey art auctions, “has emerged as the modern day purohit.” Each purohit is head priest of a particular style. Says Karanjawala, “Harish is the closest example in today's bar to Fali Nariman; Rohinton has the best law library in his brain; Mukul is easily India's busiest lawyer while Manu Singhvi is the greatest multi-tasker.” Salve has managed a fine balancing act where he has represented Mulayam Singh Yadav and Mayawati, Parkash Singh Badal and Amarinder Singh, Lalit Modi and Subhash Chandra and even the Ambani brothers, of course in different cases. Jethmalani is the man to call for anyone in trouble. In judicial circles he is known as the first resort for the last resort. Even Jethmalani’s junior Satish Maneshinde, who came to Mumbai in I993 as a penniless law graduate from Karnataka, shot to fame (and wealth) after he got bail for Sanjay Dutt in 1996. Now he owns a plush office in Worli and has become a one-stop shop for celebrities in trouble.Which of the following is not true about Ram Jethmalani?
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