Choice Strategies

As mentioned previously, the nice thing about multiple-choice test is that the answer is provided for you— all you have to do is identify it. 

Circle or underline key words and phrases in the question. These are words and phrases that help you pick the one correct answer. Think of them as clues. You are the detective and you must examine each question closely for clues to the correct answer. For example, if you have a reading comprehension passage about improvements in bicycle safety and then the question, The modern bicycle has all the following safety features EXCEPT, the key words are modern, safety features, and except. After you mark these words and phrases, look in the passage for the safety features of the modern bicycle. Then choose the answer that is not mentioned in the passage as a safety feature of the modern bicycle. 

If you aren t sure about the answer to a question, should you guess In a nutshell, the answer is yes. On the GRE, you are penalized for an incorrect answer exactly the same as you would be if you left the question blank. If you guess, even wildly, you might get lucky and increase your score. So eliminate as many wrong answers as possible, then guess. 

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Hie arid approach Desert gardens demand good water conservation and careful plant choice—strategies useful to all organic gardeners. 

Response choice strategy a numerical score based on the number of times the animal, on leaving an arm, visits the next or next-but-one arm in the same direction. 

We are using a material-choice strategy inspired by the work of M.F. Ashby and D. Cebon from the University of Cambridge [ASH 04]. To begin with, we need to express each of the functions listed above in terms of properties of the material. Then, we hierarchically rank the materials and finally make a selection on the basis of the available maximum values. 

To solve the Kohn-Sham equations a number of different approaches and strategies have been proposed. One important way in which these can differ is in the choice of basis set for expanding the Kohn-Sham orbitals. In most (but not all) DPT programs for calculating the properties of molecular systems (rather than for solid-state materials) the Kohn-Sham orbitals are expressed as a linear combination of atomic-centred basis functions ... 

We have said that the Schroedinger equation for molecules cannot be solved exactly. This is because the exact equation is usually not separable into uncoupled equations involving only one space variable. One strategy for circumventing the problem is to make assumptions that pemiit us to write approximate forms of the Schroedinger equation for molecules that are separable. There is then a choice as to how to solve the separated equations. The Huckel method is one possibility. The self-consistent field method (Chapter 8) is another. 

Catalyst Selection. The choice of catalyst is one of the most important design decisions. Selection is usually based on activity, selectivity, stabiUty, mechanical strength, and cost (31). StabiUty and mechanical strength, which make for steady, long-term performance, are the key characteristics. The basic strategy in process design is to minimize catalyst deactivation, while optimizing pollutant destmction. 

The selection of controlled and manipulated variables is of crucial importance in designing a control system. In particular, a judicious choice may significantly reduce control loop interactions. For the blending process in Fig. 8-40(d ), a straightforward control strategy would be to control x by adjusting w, and w by adjusting Wg. But... 

Intramolecular nucleophilic displacement reactions of aromatic nitro group by various nucleophiles include cydization reactions, which provide practical methods for the synthesis of a variety of heterocycles. 1 hope that the text of this review suggests a wide range of potential of this reaction in organic synthesis of various heterocycles. However, it is necessary to stress that some structural types described in this review could be prepared with similar, or even better yields by other methods. In spite of this, there are many heterocyclic systems for the synthesis of which the denitrocyclization strategy is a method of choice. 

Strategy Identify the functional group in the product (an alkyl bromide) and work the problem retrosynthetically. "What is an immediate precursor of an alkyl bromide " Perhaps an alkene plus HBr. Of the two possibilities, addition of HBr to 1-pentene looks like a better choice than addition to 2-peritene because the latter reaction would give a mixture of isomers. 

Strategy The setup is identical with that in Example 13.7. However, you will find, on solving for x, that x > 0.050a, so the approximation a — x a fails. The simplest way to proceed is to use the calculated value of x to obtain a better estimate of [HNOJ, then solve again for [H+], An alternative is to use the quadratic formula. (This is a particularly shrewd choice if you have a calculator that can be programmed to solve quadratic equations.)... 

In developing synthetic strategies for macrocycles related to corrins, one initial choice has to be made, i.e. whether to incorporate the direct link between rings A and D or to generate it in the final cyclization step. Examples of both approaches have been reported, but syntheses in which the direct link is formed in the final cyclization are more numerous. The total syntheses of vitamin B12 by Woodward/Eschenmoser and Eschenmoser are prominent examples for the realization of both strategies. 

Choice of operating strategy has a significant effect on substrate conversion, product susceptibility to contamination and process reliability. 

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