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beks73 [17]
3 years ago
13

Which of the following statements about 13C NMR is not true?A. In 13C proton-decoupled NMR spectra, all peaks are singlets.B. 13

C NMR spectra display peaks for only carbons that bear hydrogen atoms.C. 13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts.D. 13C NMR easily differentiates between the different hybridized carbons (sp3, sp2, and sp hybridized carbons).organic-chemistry
Chemistry
1 answer:
adoni [48]3 years ago
4 0

Answer: .B. 13C NMR spectra display peaks for only carbons that bear hydrogen atoms.

Explanation:

The statements that are true about 13C NMR are:

A. In 13C proton-decoupled NMR spectra, all peaks are singlets.

C 13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts.

D. 13C NMR easily differentiates between the different hybridized carbons (sp3, sp2, and sp hybridized carbons).organic-chemistry

Therefore, the option that isn't true is option B. "13C NMR spectra display peaks for only carbons that bear hydrogen atoms". This is false because 13C NMR will show every peak in the spectrum and it doesn't matter if it's only carbons that bear hydrogen atoms as everything will be shown.

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Choose the correct net ionic equation for the reaction (if a reaction occurs) between CaCl2 and AgNO3: Group of answer choices
Levart [38]

Answer:

2Ag⁺(aq) + 2Cl⁻(aq) -> 2AgCl(s)

Explanation:

Silver nitrate and calcium chloride will react in a double displacement reaction (which has to produce a precipitate, a gas, or water to have a reaction).

This reaction will produce a silver chloride precipitate and a solution of calcium nitrate.

The reaction will be 2AgNO3(aq) + CaCl2(aq) -> 2AgCl(s) + Ca(NO3)2(aq)

To write a net ionic equation:

1. Write the balanced molecular equation.

   2AgNO3 + CaCl2 -> 2AgCl(ppt) + Ca(NO3)2

2. Write the balanced complete ionic equation.

To write the complete ionic equation:

- Start with a balanced molecular equation.

2AgNO3(aq) + CaCl2(aq) -> 2AgCl(s) + Ca(NO3)2(aq)

- Break all soluble strong electrolytes (compounds with (aq) beside them) into their ions

       indicate the correct formula and charge of each ion

       indicate the correct number of each ion

       write (aq) after each ion

- Bring down all compounds with (s), (l), or (g) unchanged.

2Ag⁺(aq) + 2NO³⁻(aq) + Ca²⁺(aq) + 2Cl⁻(aq) -> 2AgCl(s) + Ca²⁺(aq) + 2NO³⁻(aq)

3. Cross out the spectator ions that are present. Spectator ions are ions that are present in the reaction mixture but do not participate in it. You can recognize spectator ions by looking for ions that are present on both sides of the equation.

4. Write the "leftovers" as the net ionic equation.

2Ag⁺(aq) + 2Cl⁻(aq) -> 2AgCl(s)

4 0
3 years ago
citric acid has an acid dissociation constant of 8.4 x 10^-4 it would be most effective for preparation of a buffer with a pH of
Sloan [31]

Answer:

(B) 3

Explanation:

Citric acid has an acid dissociation constant (Ka) of 8.4 × 10⁻⁴. When it forms a buffer with its conjugate base (citrate), we can calculate the pH using the Henderson-Hasselbalch's equation.

pH=pKa+log\frac{[base]}{[acid]}

The optimum range of pH is pKa ± 1. The pKa is -log Ka = -log (8.4 × 10⁻⁴) = 3.1. The buffer would be more effective for pH between 2.1 and 4.1, especially around 3.1. So the best choice is (B) 3.

5 0
3 years ago
All people who are asked to testify in a criminal case must first be issued a subpoena by law enforcement.
BigorU [14]

Answer:

Option B

Explanation:

All people who are asked to testify in a criminal case must first be issued a subpoena by law enforcement, is a "false statement" or option B. A subpoena is a request to appear in court which is usually given out by the attorneys who are a part of the case, the law enforcement does not give out subpoenas, so this is indeed a false statement.

Hope this helps.

7 0
3 years ago
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andriy [413]
Okay.. so I guess this is how it goes:

1. Rainforest
2. Temperate deciduous
3. Marine
4. Taiga
5. Tundra

Pls don't completely rely on it, this is my best guess and it's probably right except with Marine life and temperature deciduous. 70% I feel like it would temperate then marine. But check with urself again. Hope this helped..
5 0
3 years ago
How long will a 25.00 g
charle [14.2K]

Answer:

Hope it helps.

Explanation:

It decays by beta particle emission into xenon-131. After eight days have passed, half of the atoms of any sample of iodine-131 will have decayed, and the sample will now be 50% iodine-131 and 50% xenon-131

3 0
3 years ago
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