Numerade

Questions asked

INSTANT ANSWER

Rank the compounds in each of the following groups in order of their reactivity to electrophilic substitution: (a) Nitrobenzene, phenol, toluene, benzene (b) Phenol, benzene, chlorobenzene, benzoic acid (c) Benzene, bromobenzene, benzaldehyde, aniline

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ANSWERED

Ashwin Banarsee

Numerade educator

As a chicken develops from an egg, it becomes more ordered with time. Does this violate the principle of entropy? Explain.

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AWAITING AN EDUCATOR

What is the largest $n$ for which one can solve within a day using an algorithm that requires $f(n)$ bit operations, where each bit operation is carried out in $10^{-11}$ seconds, with these functions $f(n) ?$ $$ \begin{array}{llll}{\text { a) } \log n} & {\text { b) } 1000 n} & {\text { c) } n^{2}} \\ {\text { d) } 1000 n^{2}} & {\text { e) } n^{3}} & {\text { f) } 2^{n}} \\ {\text { g) } 2^{2 n}} & {\text { h) } 2^{2^{n}}}\end{array} $$

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ANSWERED

Darshan Maheshwari

Numerade educator

A person holding a lunch bag is moving upward in a hot air balloon at a constant speed of 7.0 m/s. When the balloon is 24 m above the ground, she accidentally releases the bag. What is the speed of the bag just before it reaches the ground?

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ANSWERED

Stephen Ho

Numerade educator

Aspirin can be made in the laboratory by reacting acetic anhydride (C4H6O3) with salicylic acid (C7H6O3) to form aspirin (C9H8O4) and acetic acid (C2H4O2). The balanced equation is: C4H6O3 + C7H6O3-C9H8O4 + C2H4O2 In a laboratory synthesis, a student begins with 3.00 mL of acetic anhydride (density = 1.08 g>mL) and 1.25 g of salicylic acid. Once the reaction is complete, the student collects 1.22 g of aspirin. Determine the limiting reactant, theoretical yield of aspirin, and percent yield for the reaction.

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ANSWERED

C D

Numerade educator

Which complex is not involved in producing the electromotive force of ATP synthesis? a. ATP synthase b. cytochrome complex c. Photosystem I d. Photosystem II

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INSTANT ANSWER

Who's charged? Draw the structure of the dipeptide Gly-His. What is the charge on the peptide at $\mathrm{pH}$ 4.0? At pH 7.5?

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ANSWERED

Tracy Tourville

Numerade educator

Working with Buffers A buffer contains 0.010 mol of lactic acid (pK $_{\mathrm{a}}=3.86$ ) and 0.050 mol of sodium lactate per liter. (a) Calculate the pH of the buffer. (b) Calculate the change in $\mathrm{pH}$ when $5 \mathrm{mL}$ of $0.5 \mathrm{M}$ HCl is added to $1 \mathrm{L}$ of the buffer. (c) What pH change would you expect if you added the same quantity of HCl to 1 L of pure water?

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INSTANT ANSWER

A 50 -kg crate is attached to the trolley-beam system shown. Knowing that $a=1.5 \mathrm{m},$ determine $(a)$ the tension in cable $C D,(b)$ the reaction at $B .$

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INSTANT ANSWER

A rectangular plate is rotating with a constant angular speed about an axis that passes perpendicularly through one corner, as the drawing shows. The centripetal acceleration measured at corner $A$ is $n$ times as great as that measured at corner $B$. What is the ratio $L_{1} / L_{2}$ of the lengths of the sides of the rectangle when $n=2.00 ?$

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Nate I.