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Nookie1986 [14]
3 years ago
15

How many neutrons does element X have if its atomic number is 20 and its mass number is 82?

Chemistry
1 answer:
snow_tiger [21]3 years ago
6 0
Protons = Atomic number
Protons + Neutrons = Mass Number
Protons = 20
Neutrons = Atomic number - Mass number
Neutrons = 82 - 20 = 62 
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Enough of a monoprotic weak acid is dissolved in water to produce a 0.0144 0.0144 M solution. The pH of the resulting solution i
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Answer:

The value of dissociation constant of the monoprotic acid is 1.099\times 10^{-3}.

Explanation:

The pH of the solution = 2.46

pH=-\log[H^+]

2.46=-\log[H^+]

[H^+]=0.003467 M

HA\rightleftharpoons H^++A^-

Initially

0.0144         0      0

At equilibrium

(0.0144-x)       x       x

The expression if an dissociation constant is given by :

K_a=\frac{[A^-][H^+]}{[HA]}

K_a=\frac{x\times x}{(0.0144-x)}

x=[H^+]=0.003467 M

K_a=\frac{0.003467 \times 0.003467 }{(0.0144-0.003467 )}

K_a=1.099\times 10^{-3}

The value of dissociation constant of the monoprotic acid is 1.099\times 10^{-3}.

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3 years ago
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Answer:

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Explanation:

5 0
2 years ago
Which statements correctly describe the decay rates of radioactive isotopes?
storchak [24]

Answer: b} The exact time when an individual atom will decay can be accurately predicted.

c} After each half-life, the amount of radioactive material is reduced by half.

Explanation:

All radioactive decay  follows first order kinetics.

Rate law expression for first order kinetics is given by:

t=\frac{2.303}{k}\log\frac{a}{a-x}

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4 0
3 years ago
Read 2 more answers
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Galina-37 [17]

Answer:

Explanation:

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2 years ago
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Amanda [17]

Answer: The density of the material is 2.66 g/mL and it is likely this  is made of Aluminum

Explanation:

The first step to know the material of the chunk of metal is to calculate its density. The general formula for density is P (density) = \frac{m (mass)}{ v (volume)}. Moreover, in this case, it is known the mass is 37.28 g, but the volume is not directly provided. However, we know the water in the graduated cylinder had a volume of 20.0 mL and this increased to 34.0 mL when the chunk of metal is added, this means the volume of the metal is 14 mL (34.0 mL - 20.0 mL = 14 mL). Now let's calculate the density:

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