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3 years ago

The teacher shows students a pictorial model of an atom. Which element is

Chemistry

1 answer:

frutty [35]3 years ago

4 0

Answer:

C. Fluorine because the model has 9 protons which is represented by the atomic number

Explanation:

We usually identify an element by the number of protons in them. The number of protons is the atomic number of an atom.

Every atom has a specific number of protons in them.
This number of protons is the atomic number.
According to the periodic law, atoms are arranged on the periodic table based on their atomic number.
The given fluorine atom has 9 protons which represents the atomic number of the atom.
This way, the given number clearly shows the right model for identifying the chemical specie.

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A sample of aluminum absorbs 9.86 J of heat, upon which the temperature increases from 23.2°C to 30.5°C. Since the specific heat

True [87]

Answer:

1.50 g

Explanation:

The heat absorbed by the aluminum in this case is:

q = m x C x ΔT m= q/ (C x ΔT)

q= 9.86 J

C = 0.90 J/g-K

ΔT = ( 30.5 ºC - 23.2 ºC ) = 7.3 ºC = 7.3 K (this is a range of temperature)

m = 9.86 J / ( 0.90 J/g-K ) x 7.3 K ) = 1.50 g

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3 years ago

The pK1, pK2, and pKR of the amino acid lysine are 2.2, 9.1, and 10.5, respectively. The pK1, pK2, and pKR of the amino acid arg

almond37 [142]

Answer:

pH 9,8 is likely to work best for this separation

Explanation:

Ion exchange chromatography is a chemical process where molecules are separated by affinity to an ion exchange resin. To separate different aminoacids you must use the isoelectric point (That is the pH where the aminoacid will be in its neutral form).

For lysine, PI is:

$pH = \frac{1}{2} (9,1+10,5) =$ 9,8

For arginine:

$pH = \frac{1}{2} (9,0+12,5) =$ 10,75

At pH = 9,8 lysine will be in its neutral form and will not be retain in the column but arginine will be in +1 charge being retained by the ion exchange resin.

Thus, pH 9,8 is likely to work best for this separation

I hope it helps!

5 0

3 years ago

What properties does a substance have to have to be a mineral?.

UkoKoshka [18]

Answer:

the description of a mineral species usually includes its common physical properties such as habit, hardness, lustre, diaphaneity, colour, streak, tenacity, cleavage, fracture, parting, specific gravity, magnetism, fluorescence, radioactivity, as well as its taste or smell and its reaction to acid.

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2 years ago

Convert 65.4 m to mm. Helppp please

Ostrovityanka [42]

Answer:65.4 meters= 65400 millimeters

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Which formula shows a substance that is not molecular?

Scrat [10]

H ( hydrogen ) is the answer I believe.

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3 years ago

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