The element copper has two stable isotopes, copper-63 with a mass of 62.93 amu and copper-65 with a mass of 64.93 amu. From the atomic weight of Cu = 63.54 one can conclude that:

- both isotopes have the same percent natural abundance
- copper-65 has the highest percent natural abundance
- most copper atoms have an atomic mass of 63.54
- copper-63 has the highest percent natural abundance

Molality  is the measure of concentration of solute in 1 kg of solution. The molality of the solution is 3.05 mol/kg.

10% of HCl (by mass) means 10 g of HCl and in 90 g of water.

Molar mass of HCl = 36.5 g/mol

Molality:

It is the measure of concentration of solute in 1 kg of solution. It can be calculated by the formula.

[tex]\bold {m = \dfrac {n }{w}\times 1000}[/tex]

Where,

m- molality

n - number of moles

w - weight of solvent in grams

Number of moles of HCl

[tex]\bold {n = \dfrac w{m} = \dfrac {10}{36.5} = 0.274 g}[/tex]

put the value in molality formula,

[tex]\bold {m = \dfrac {0.274 }{90}\times 1000}\\\\\bold {m = 3.05\ g/mol}[/tex]

Therefore, the molality of the solution is 3.05 mol/kg.

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Final answer:

To calculate the molarity of a 10.0% HCl solution, convert 10 grams of HCl to moles, and then divide by the volume of the solution in liters. This results in a molarity of 2.74 M.

Explanation:

To calculate the molarity of a 10.0% (by mass) aqueous solution of hydrochloric acid (HCl), start by understanding that a 10.0% solution means there are 10 grams of HCl in 100 grams of the solution. First, since the solution is aqueous, we can assume the density is close to that of water, which is approximately 1 g/mL, so 100 grams of the solution is roughly equivalent to 100 mL (0.1 L) of solution.

Next, convert the mass of HCl to moles. The molar mass of HCl is about 36.46 g/mol:

10 grams HCl × (1 mol HCl / 36.46 grams) = 0.274 moles HCl

Then, divide the moles of HCl by the volume of the solution in liters to find the molarity:

Molarity = Moles of solute / Volume of solution in liters

Molarity = 0.274 moles HCl / 0.1 L = 2.74 M

The molarity of the 10.0% HCl solution is therefore 2.74 M.

Answer: No hydrogen bond cannot occur in this alpha helix structure.

Explanation: For hydrogen bond to form, the electronegativity difference should be more than 1.7. carbon has an electronegativity of 2.5 whereas hydrogen has 2.1 so their electronegativity difference is 0.3. So in this alpha helix structure cannot occur.

Answer: A. contains 18 electrons

Explanation:

Atomic number is defined as the number of protons or number of electrons that are present in an atom. It is characteristic of an element.

Atomic number of phosphorous is 15.

The electronic configuration of phosphorous (P) will be,

[tex]P:15:1s^22s^22p^63s^23p^3[/tex]

Atomic number = Number of electrons = Number of protons = 15

As the phosphorous atom has gained 3 electrons, it will have 15+3= 18 electrons , the phosphorous anion will be having a charge of -3.

The electronic configuration of [tex]P^{3-}[/tex] will be,

[tex]P^{3-}:18:1s^22s^22p^63s^23p^6[/tex]

Thus the correct statement is this ion contains 18 electrons

The phosphide ion contains 18 electrons. The correct answer is Option A.

The ion formed by phosphorus, called phosphide, has the formula P3−. To determine its properties, we can look at its electron configuration. Phosphorus has an atomic number of 15, meaning it has 15 electrons in its neutral state. When phosphorus forms the phosphide ion (P3−), it gains three extra electrons to achieve a stable electron configuration. So, the phosphide ion contains a total of 18 electrons.

Therefore, the correct answer is A. The ion contains 18 electrons.

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The question is incomplete, here is the complete question:

A chemist adds 345.0 mL of a 0.0013 mM (MIllimolar) copper(II) fluoride [tex]CuF_2[/tex] solution to a reaction flask.

Calculate the mass in micrograms of copper(II) fluoride the chemist has added to the flask. Be sure your answer has the correct number of significant digits.

Answer: The mass of copper (II) fluoride is 0.13 mg

Explanation:

We are given:

Millimolarity of copper (II) fluoride = 0.0013 mM

This means that 0.0013 millimoles of copper (II) fluoride is present in 1 L of solution

Converting millimoles into moles, we use the conversion factor:

1 moles = 1000 millimoles

So, [tex]0.0013mmol\times \frac{1mol}{1000mmol}=1.3\times 10^{-6}mol[/tex]

To calculate the number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

We are given:

Moles of copper (II) fluoride solution = [tex]1.3\times 10^{-6}mol[/tex]

Molar mass of copper (II) fluoride = 101.5 g/mol

Putting values in above equation, we get:

[tex]1.3\times 10^{-6}mol=\frac{\text{Mass of copper (II) fluoride}}{101.5g/mol}\\\\\text{Mass of copper (II) fluoride}=(1.3\times 10^{-6}mol\times 101.5g/mol)=1.32\times 10^{-4}g[/tex]

Converting this into milligrams, we use the conversion factor:

1 g = 1000 mg

So,

[tex]\Rightarrow 1.32\times 10^{-4}g\times (\frac{1000mg}{1g})=0.13mg[/tex]

Hence, the mass of copper (II) fluoride is 0.13 mg

Answer:

The mass of copper(II) fluoride is 45.54 micrograms

Explanation:

A chemist adds 345.0 mL  of a 0.0013 mM copper(II) fluoride solution to a reaction flask. Calculate the mass in micrograms of copper(II) fluoride the chemist has added to the flask. Round your answer to significant digits.

Step 1: Data given

Molarity of the copper(II) fluoride solution = 0.0013 mM =

Volume of the solution 345.0 mL = 0.345 L

Molar mass copper(II) fluoride = 101.54 g/mol

Step 2: Calculate moles of copper(II) fluoride

Moles CuF2 = molarity * volume

Moles CuF2 = 0.0000013 M * 0.345 L

Moles CuF2 = 0.0000004485 moles

Step 3: Calculate mass of  CuF2

Mass CuF2 = moles * Molar mass

Mass CuF2 = 0.0000004485 moles * 101.54 g/mol

Mass CuF2 = 0.00004554 grams = 0.04554 miligrams = 45.54 micrograms

The mass of copper(II) fluoride is 45.54 micrograms

Answer: option B and option C

Explanation: