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Mamont248 [21]
3 years ago
14

An atom has an atomic number of 19 and mass number of 39 how many electrons and protons does it have? ​

Chemistry
1 answer:
LuckyWell [14K]3 years ago
5 0

Answer:

19 protons, 20 neutrons and 18 electrons.

Explanation:

The atomic number gives the number of protons 19

p = 19

The atomic mass is the sum of the protons and neutrons

p + n = 39   p = 19

put p into the equation and solve for n the neutrons.

19 + n = 39

Subtract 19 from both sides

19 − 19 + n = 39 − 19

n = 20

The number of electrons equals the number of protons in a neutral atom. The positive charge equals the negative charge. The negative charge is the number of electrons. This ion has a charge of +1. So solve for the negative charge.

− 19 + 1 = − 18

The negative charge is -18 so

e = 18

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The molecular ion is not visible in the mass spectrum of 2-chloro-2- methylpropane. At what m/z value would the molecular ion be
pochemuha

Answer:  hello the complete question is attached below

Visibility of molecular ion = m/z value of 77

Explanation:

For The molecular ion to be visible, it has to be at an m/z value of 77 and this is because molecular ions will have an m/z ratio =  molecular mass of given molecule in most cases but not always in all cases.

And the visibility is possible after the removal of CH₃ ion.

ii) Evidence in the mass spectrum that suggests peak at m/z = 77

attached below

5 0
3 years ago
In which direction does a bag at rest move when a force of 20 newtons is applied from the right?
kow [346]

Answer: B!

Explanation: In the direction opposite of the direction of the applied force.There is no force in the other side being applied.

3 0
3 years ago
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Please help due in 5 min. I need this to be done or my grade will drop from a 96 to a 32.
ratelena [41]

Answer:

E = 3.035× 10-¹⁹J = 1.9eV

f = 4.58 × 10¹⁴Hz

Explanation:

wavelength = 6.55 × 10-⁷m

c = 3 × 10⁸m/s

f = ?

E = ?

a) f = c/wavelength

f = 3 × 10⁸/6.55 × 10-⁷

f = 4.58 × 10¹⁴Hz

b) E = hc/wavelength

E = 6.626×10-³⁴ × 3 × 10⁸/ 6.55 × 10-⁷

E = 3.035 × 10-¹⁹J

1ev = 1.6 × 10-¹⁹J

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3 0
3 years ago
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How many half-lives have passed if the amount of Parent Isotope is 12.5%?
OverLord2011 [107]

Answer:

Three half lives.

Explanation:

Given data:

Number of half lives passed = ?

Amount of parent isotope left = 12.5%

Solution:

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At second half life = 50%/2 = 25%

At third half life = 25%/2 = 12.5%

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7 0
3 years ago
The ksp of calcium carbonate, caco3, is 3.36 × 10-9 m2. calculate the solubility of this compound in g/l.
maw [93]
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                       CaCO₃(s) ⇄ Ca²⁺(aq) + CO₃²⁻(aq)
Initial                Y                   -                 -
Change           -X                  +X              +X
Equilibrium      Y-X                 X                X

Ksp for the CaCO₃(s) is 3.36 x 10⁻⁹ M²

                Ksp = [Ca²⁺(aq)][CO₃²⁻(aq)]
3.36 x 10⁻⁹ M² = X * X
3.36 x 10⁻⁹ M² = X²
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Hence the solubility of CaCO₃(s) = 5.79 x 10⁻⁵ M
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Molar mass of CaCO₃ = 100 g mol⁻¹

Hence the solubility of CaCO₃ = 5.79 x 10⁻⁵ mol/L x 100 g mol⁻¹
                                                 = 5.79 x 10⁻³ g/L

7 0
3 years ago
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