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Anit [1.1K]
3 years ago
6

At a local hospital, 35 babies were born. If 25 were boys, what percentage of the newborns were boys?

Chemistry
1 answer:
marishachu [46]3 years ago
3 0
\%_{b}=\frac{25*100\%}{35}\approx71,43\%
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Calculate the molarity when 135 g of KCl is dissolved to make a 2.50 L solution. Round to two significant digits.
inysia [295]
<h2>0.72 mol/L</h2>

Explanation:

       \textrm{Molarity of a solution}=\frac{\textrm{Number of moles of solvent}}{\textrm{Volume of solution in Liters}}

       We are given a 2.50L solution which contains 135g of KCl.

       To calculate number of moles of KCl present, we need to find it's molar mass from charts. Molar Mass of KCl is known to be 74.55\frac{g}{Mol}.

       Number of moles of KCl present = \frac{\textrm{Given weight}}{\textrm{Molar Mass}}\textrm{ = }\frac{135g}{74.55\frac{g}{Mol}}\textrm{ = }1.81087mol

       Molarity = \frac{1.81087mol}{2.50L}=0.7243\frac{mol}{L}

∴ Molarity of given KCl solution = 0.72\frac{mol}{L}

7 0
3 years ago
Sulfur dioxide, SO2(g), can react with oxygen to produce sulfur trioxide, SO3(g), by the following reaction
WITCHER [35]

Answer:

The heat produced is -15,1kJ

Explanation:

For the reaction:

2SO₂+O₂ → 2SO₃

The enthalpy of reaction is:

ΔHr = 2ΔHf SO₃ - 2ΔHf SO₂

As ΔHf SO₃ = -395,7kJ and ΔHf SO₂ = -296,8kJ

<em>ΔHr = -197,8kJ</em>

Using n=PV/RT, the moles of reaction are:

n = \frac{1,00atm*3,75L}{0,082atmL/molK*298,15K} = <em>0,153 moles of reaction</em>

As 2 moles of reaction produce -197,8kJ of heat, 0,153moles produce:

0,153mol×\frac{-197,8kJ}{2mol} = <em>-15,1kJ</em>

<em></em>

I hope it helps!

8 0
3 years ago
For some hypothetical metal the equilibrium number of vacancies at 750°C is 2.8 × 1024 m−3. If the density and atomic weight of
mash [69]

Answer:

The correct answer is 5.447 × 10⁻⁵ vacancies per atom.

Explanation:

Based on the given question, the at 750 degree C the number of vacancies or Nv is 2.8 × 10²⁴ m⁻³. The density of the metal is 5.60 g/cm³ or 5.60 × 10⁶ g/m³. The atomic weight of the metal given is 65.6 gram per mole. In order to determine the fraction of vacancies, the formula to be used is,  

Fv = Nv/N------ (i)  

Here Nv is the number of vacancies and N is the number of atomic sites per unit volume. To find N, the formula to be used is,  

N = NA×P/A, here NA is the Avogadro's number, which is equivalent to 6.022 × 10²³ atoms per mol, P is the density and A is the atomic weight. Now putting the values we get,  

N = 6.022 × 10²³ atoms/mol × 5.60 × 10⁶ g/m³ / 65.6 g/mol

N = 5.14073 × 10²⁸ atoms/m³

Now putting the values of Nv and N in the equation (i) we get,  

Fv = 2.8 × 10²⁴ m⁻³ / 5.14073 × 10²⁸ atoms/m^3

Fv = 5.44669 × 10⁻⁵ vacancies per atom or 5.447 × 10⁻⁵ vacancies/atom.  

4 0
3 years ago
Draw the structure of the compound C9H12 from its proton (1H) NMR spectrum below. First-order spin-spin splitting rules and equa
Vikki [24]

Answer:

Isopropylbenzene

Explanation:

If you draw the structure, you can see that there are two methyl groups and in between there.

Adjacent to CH3, there are four neighbouring hydrogens, therefore, n=4+1 = 5. The same is for methyl on other side. For carbon present in benzene ring,  there is 2, since there is one hydrogen on benzene per carbon.

4 0
4 years ago
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Consider the cell described below at 259 K: Ni | Ni2+ (1.15 M) || Fe3+ (2.23 M) | Fe Given the standard reduction potentials fou
likoan [24]

Answer:

i dont know sorry :(

Explanation:

8 0
3 years ago
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