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zubka84 [21]
3 years ago
11

What is the product of a positron and electron combining then undergoing annihilation during the pet imaging process? a. two 511

kev photons are formed. b. x-rays are formed. c. a single gamma ray is formed. d. two high-speed beta particles are formed?
Chemistry
1 answer:
jekas [21]3 years ago
5 0
Answer is: <span>a. two 511 kEv photons are formed.
</span><span>When the positrons reach thermal energies, they start to interact with electrons by annihilation.</span>
Positron-emission tomography<span> (</span>PET)<span> is a </span>nuclear medicine functional imaging<span> technique that is used to observe metabolic processes in the body. The system detects pairs of </span>gamma rays<span> emitted indirectly by a </span>positron<span>-emitting </span>radionuclide.
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How humans can utilise the carbon cycle
Advocard [28]

Explanation:

Burning fossil fuels, changing land use, and using limestone to make concrete all transfer significant quantities of carbon into the atmosphere

5 0
2 years ago
If 1 mol of XO₂ contains the same number of atoms as 60 g of XOs, what is the molar mass of XO₂?
Lena [83]

Answer:

44 grams/mole

Explanation:

<u>If 1 mol of XO₂ contains the same number of atoms as 60 g of XO3, what is the molar mass of XO₂?</u>

<u></u>

60 grams of XO3 is one mole XO3, since it has the same number of atoms as 1 mole of XO2.

Let c be the molar mass of X.  The molar mass of XO3 is comprised of:

X:  c

3O:  3 x 16 = 48

Total molar mass of XO3 is = <u>48 + c</u>

We know that the molar mass of XO3 = 60 g/mole, so:

48 + c  = 60 g/mole

c = 12 g/mole

The molar mass of XO2 would be:

1 X = 12

2 O = 32

Molar mass = 44 grams/mole, same as carbon dioxide.  Carbon's molar mass is 12 grams.

<u></u>

<u></u>

5 0
2 years ago
Using the solubility graph place the substances in order from most soluble (#1) to least soluble at 40°C. KNO3, NaClO3,KBr, NaCl
mestny [16]

Answer:

  • NaClO₃ > KBr > KNO₃ > NaCl.

Explanation:

The attached file contains the graph with the solubility curves for the four substances, KNO₃, NaClO₃, KBr, NaCl.

To determine the solubility of each salt at a certain temperature, you read the temperature on the horizontal axis, labeled Temperature (ºC), and move upward up to intersecting the curve of the corresponding salt. Then, move horizontally up to insersceting the vertical axis, labeled Solubility (g/100g of H₂O), to read the solubility.

The higher the reading on the vertical axis, the higher the solubility.

The red vertical line that I added is at a temperature of 40ºC.

The number in blue indicate the order in which the solubility curves are intersected at that temperature:

  • 4: NaCl: this is the lowest solubility
  • 3: KNO₃: this is the second lowest solubility
  • 2: KBr: this is the third lowest solubility
  • 1: NaClO₃: this is the highest solubility.

Thus, the rank, from most soluble to least soluble is:

  • NaClO₃ > KBr > KNO₃ > NaCl.

7 0
3 years ago
A mixture that has two or more substances that are spread out evenly is called _____
svlad2 [7]

Answer:

D

Explanation:

heterogeneous mixture you can see the different substances that go into it.

homogeneous mixture you can't see the difference, the mixture looks like one substance.

6 0
3 years ago
For molecules with more than one ionizable groups, such as glycine, which of the following statements is true? For molecules wit
tester [92]

Answer: Option (a) is the correct answer.

Explanation:

The isoelectric point (pI) is actually the pH where a particular amino acid exists as a neutral molecule. This means that if pH equals pI then there will be no electric charge on the molecule.

Therefore, the statement at pH near the pI, nearly all the molecules carry no net charge, is true.

A buffer is composed of a solution of weak acid or base and salt of weak acid/base.So, when pH equals pI then there occurs no net charge. Hence, there will be no existence of conjugate acid-base pair.

Therefore, the statement when the pH is near the pI, the solution is near its maximum buffering ability, is false.

It is known that when pH is less than pI then there will be a net positive charge on the amino acid.

Hence, the statement at a pH near the pI, nearly all the molecules carry a net positive charge, is false.

When pH is greater than pI then amino acid will have a net negative charge. Hence, the statement at a pH near the pI, nearly all the molecules carry a net negative charge, is false.

Thus, we can conclude that out of the given options the statement at pH near the pI, nearly all the molecules carry no net charge, is true.

5 0
3 years ago
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