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kow [346]
3 years ago
5

Read the passage. Look at the underlined section marked number 9. There may be a mistake in the way the sentence is written. If

you find a mistake, choose the answer that corrects the mistake. If there is no mistake, choose ‘Correct as is.’ A) Correct as is. B) Only the ones who were known to be experts with the needle were invited for an afternoon of quilting, or all others came later for an evening of fun and dancing. C) Only the ones who were known to be experts with the needle were invited for an afternoon of quilting, for all others came later for an evening of fun and dancing. D) Only the ones who were known to be experts with the needle were invited for an afternoon of quilting, and all others came later for an evening of fun and dancing.
Chemistry
2 answers:
ludmilkaskok [199]3 years ago
8 0

Answer:

D

Explanation:

I just got it right on Usatestprep.

Alexus [3.1K]3 years ago
5 0

The answer is D just did it

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how to determine the net charge of the tripeptide Asp-Gly-Leu at pH 7. Can someone show in details and tricks on how to solve it
Ugo [173]

Answer:

0!

Explanation:

  • You need to search your pKa values for Asn (2.14, 8.75), Gly (2.35, 9.78) and Leu(2.33, 9.74), the first value corresponding to -COOH, the second to -NH3 (a third value would correspond to an R group, but in this case that does not apply), and we'll build a table to find the charges for your possible dissociated groups at indicated pH (7), we need to remember that having a pKa lower than the pH will give us a negative charge, having a pKa bigger than pH will give us a positive charge:            

           

                   -COOH         -NH3              

pH 7------------------------------------------------------              

Asn               -                      +

Gly                -                      +

Leu               -                      +

  • Now that we have our table we'll sketch our peptide's structure:

<em>HN-Asn-Gly-Leu-COOH</em>

This will allow us to see what groups will be free to react to the pH's value, and which groups are not reacting to pH because are forming the bond between amino acids. In this particular example only -NH group in Ans and -COOH in Leu are exposed to pH, we'll look for these charges in the table and add them to find the net charge:

+1 (HN-Asn)

-1 (Leu-COOH)

=0

The net charge is 0!

I hope you find this information useful and interesting! Good luck!

5 0
3 years ago
Question 1
REY [17]

Answer:

An atom of neon-20 has one fewer proton and two fewer neutrons than an atom of sodium-23.

Explanation:

Neon - 20 and Sodium - 23

Neon - 20

Protons = 10

Neutrons = 10

Sodium - 23

Protons = 11

Neutrons = 12

With the information above and checking the options;

An atom of neon-20 has one fewer proton and two fewer neutrons than an atom of sodium-23.

This option is correct.

5 0
3 years ago
Hợp chất nào có khả năng là hợp chất ion cao nhất ?<br>A Al2O3<br>B ScCl3<br>C NO2<br>D CCl4
Rzqust [24]

Answer:

B

Explanation:

hợp chất nào có khả năng là hợp chất ion cao nhất ?

A Al2O3?

B

7 0
3 years ago
Which of the following buffers will be most effective at pH 9.25? Group of answer choices a mixture of 1.0 M HC2H3O2 and 1.0 M N
ludmilkaskok [199]

Answer:

The most effective buffer at pH 9.25 will be  a mixture of 1.0 M NH3 and 1.0 M NH4Cl

Explanation:

Step 1: Data given

pH of a buffer = pKa + log ([A-]/[Ha])

a mixture of 1.0 M HC2H3O2 and 1.0 M NaC2H3O2 (Ka for acetic acid = 1.8 x 10-5)

pH = -log( 1.8 * 10^-5) + log (1/1)

pH = -log( 1.8 * 10^-5)

pH = 4.74

a mixture of 1.0 M NaCN and 1.0 M KCN (Ka for HCN = 4.9 x 10-10)

pH = -log( 4.9 * 10^-10) + log (1/1)

pH = -log( 1.8 * 10^-5)

pH = 9.30

a mixture of 1.0 M HCl and 1.0 M NaCl

The solution made from NaCl and HCl will NOT act as a buffer.

HCl is a strong acid while NaCl is salt of strong acid and strong base which do not from buffer solutions hence due to HCl PH is less than 7.

a mixture of 1.0 M NH3 and 1.0 M NH4Cl (Kb for ammonia = 1.76 x 10^-5)

Ka * Kb = 1*10^-14

Ka = 10^-14 / 1.76*10^-5

Ka = 5.68*10^-10

pH = -log( 5.68*10^-10) + log (1/1)

pH = -log( 5.68*10^-10)

pH = 9.25

The most effective buffer at pH 9.25 will be  a mixture of 1.0 M NH3 and 1.0 M NH4Cl

8 0
3 years ago
Which of the following is an example of a polymer? (2 points)
Strike441 [17]
Nylon is a polymer because it is made of a lo of molecules bonded together. 
3 0
3 years ago
Read 2 more answers
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