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Snowcat [4.5K]
3 years ago
5

The isotope of an unknown element, X, has a mass number of 79. The most stable ion of this isotope has 36 electrons and has a 22

charge. Which of the following statements is(are) true? For the false statements, correct them. (A) This ion has more electrons than protons in the nucleus. (B) The isotope of X contains 38 protons. (C) The isotope of X contains 41 neutrons. (D) The identity of X is strontium, Sr.
Chemistry
1 answer:
Tema [17]3 years ago
3 0

Answer:

A) False

B) True

C) True

D) True

Explanation:

A) False. If the charge of the atom is +2 means that you have two protons more than number of electrons. If you have 36 electrons you must have <em>38 protons.</em> Also, the electrons are not in the nucleus.

B) True. The isotope of X contains 38 protons, two more than the electron number.

C) True. The mass number is the number of protons + number of neutrons.

If the mass number is 79 and there are 38 protons you must have 41 neutrons.

D) True. You can now the identity of the atom with the number of protons that is the same than atomic number. The strontium, Sr, is the atom with 38 as atomic number.

I hope it helps!

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<h3 />

<h3>What is organic chemistry?</h3>

Organic chemistry can be simply defined as the study of organic compounds.

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Thus, we can defined organic chemistry as the the study of general properties and compositions of organic compounds.

Learn more about organic chemistry here: brainly.com/question/704297

6 0
2 years ago
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How many grams of NaF should be added to 500 mL of a 0.100 M solution of HF to make a buffer with a pH of 3.2
Korolek [52]

Answer:

2.25g of NaF are needed to prepare the buffer of pH = 3.2

Explanation:

The mixture of a weak acid (HF) with its conjugate base (NaF), produce a buffer. To find the pH of a buffer we must use H-H equation:

pH = pKa + log [A-] / [HA]

<em>Where pH is the pH of the buffer that you want = 3.2, pKa is the pKa of HF = 3.17, and [] could be taken as the moles of A-, the conjugate base (NaF) and the weak acid, HA, (HF). </em>

The moles of HF are:

500mL = 0.500L * (0.100mol/L) = 0.0500 moles HF

Replacing:

3.2 = 3.17 + log [A-] / [0.0500moles]

0.03 = log [A-] / [0.0500moles]

1.017152 = [A-] / [0.0500moles]

[A-] = 0.0500mol * 1.017152

[A-] = 0.0536 moles NaF

The mass could be obtained using the molar mass of NaF (41.99g/mol):

0.0536 moles NaF * (41.99g/mol) =

<h3>2.25g of NaF are needed to prepare the buffer of pH = 3.2</h3>
4 0
3 years ago
Which beaker has the least thermal energy?
Debora [2.8K]

Answer:

Breaker A

Explanation:

Because the temperature is cooler in A then the rest

3 0
3 years ago
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How many grams of NaCl (molecular weight = 58.4 g mole-1) would you dissolve in water to make a total volume of 500 mL of soluti
kolezko [41]

Given :

Volume , V = 500 mL .

Molarity , M = 0.5 M .

Molecular mass of NaCl is 58.4\ g/mole .

To Find :

How many grams of NaCl is required .

Solution :

Let , NaCl required is x gram .

Molarity is given by :

M=\dfrac{\text{Number of moles}}{\text{Volume (in liters) }}\\\\M=\dfrac{m}{M\times V}\\\\0.5=\dfrac{x}{58.4\times 0.5}\\\\x=0.5^2\times 58.4\ g\\\\x=14.6\ g

Hence , this is the required solution.

6 0
3 years ago
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