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wariber [46]
3 years ago
9

Sodium is going in group 1, period 3. It contains A. One valence electron in its 3rd energy shell B three valence electron in it

s 1st energy shell C. 11 protons, 11electrons , 11 neutrons D. 11 protons, 11 electrons and 23 neutrons
Chemistry
1 answer:
topjm [15]3 years ago
5 0

Answer:

The correct answer is option A, that is, one valence electron in its third energy shell and option C, that is, 11 electrons and 11 protons.

Explanation:

The outermost electrons and the ones that take part in the process of bonding are termed as valence electrons. The atomic number of sodium is 11, thus, it possesses 11 protons and the atoms are neutral so it suggests that sodium has 11 electrons. By electronic configuration, it can be seen that in sodium, two electrons are present in the first shell, 8 in the second, and only one electron in the third shell, that is, 2.8.1. The electron present in the third shell is the valence electron.

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Tracie measured 87.47 mg of cholesterol in 0.03 mL of blood. What is the density of this mixture in g/mL?
Lelu [443]

We can use a simple equation to solve this problem.


d = m/v


Where d is the density, m is the mass and v is the volume.


d = ?

m = 87.47 mg = 87.47 x 10⁻³ g

v = 0.03 mL


By applying the equation,

  d = 87.47 x 10⁻³ g / 0.03 mL

  d = 2.92 g/mL



Hence, the density of the mixture is 2.92 g/mL.


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3 years ago
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3 years ago
A gaseous mixture composed of 20% CH4, 30% C2H4, 35% C2H2, and 15% C2H20. What is the average molecular weight of the mixture? a
Semenov [28]

<u>Answer:</u> The correct answer is Option d.

<u>Explanation:</u>

We are given:

Mass percentage of CH_4 = 20 %

So, mole fraction of CH_4 = 0.2

Mass percentage of C_2H_4 = 30 %

So, mole fraction of C_2H_4 = 0.3

Mass percentage of C_2H_2 = 35 %

So, mole fraction of C_2H_2 = 0.35

Mass percentage of C_2H_2O = 15 %

So, mole fraction of C_2H_2O = 0.15

We know that:

Molar mass of CH_4 = 16 g/mol

Molar mass of C_2H_4 = 28 g/mol

Molar mass of C_2H_2 = 26 g/mol

Molar mass of C_2H_2O = 48 g/mol

To calculate the average molecular mass of the mixture, we use the equation:

\text{Average molecular weight of mixture}=\frac{_{i=1}^n\sum{\chi_im_i}}{n_i}

where,

\chi_i = mole fractions of i-th species

m_i = molar masses of i-th species

n_i = number of observations

Putting values in above equation:

\text{Average molecular weight}=\frac{(\chi_{CH_4}\times M_{CH_4})+(\chi_{C_2H_4}\times M_{C_2H_4})+(\chi_{C_2H_2}\times M_{C_2H_2})+(\chi_{C_2H_2O}\times M_{C_2H_2O})}{4}

\text{Average molecular weight of mixture}=\frac{(0.20\times 16)+(0.30\times 28)+(0.35\times 26)+(0.15\times 42)}{4}\\\\\text{Average molecular weight of mixture}=6.75

Hence, the correct answer is Option d.

3 0
3 years ago
How many dm³ of hydrogen,measured at s.t.p.,would be needed to reduce 47.7g of copper(II) oxide to copper?
GaryK [48]

Answer:

Option D. 13.44

Explanation:

We'll begin by calculating the number of mole in 47.7g of copper(II) oxide, CuO.

This can be obtained as follow:

Mass of CuO = 47.7 g

Molar mass of CuO = 63.5 + 16 = 79.5 g/mol

Mole of CuO =.?

Mole = mass /Molar mass

Mole of CuO = 47.7/79.5

Mole of CuO = 0.6 mole

Next, we shall write the balanced equation for the reaction. This is given below:

CuO + H2 —> Cu + H2O

From the balanced equation above,

1 mole of CuO reacted with 1 mole of H2 to produce 1 mole of Cu and 1 mole of H2O.

Next, we shall determine the number of mole of H2 needed to react completely with 0.6 mole of CuO.

This can be obtained as follow:

From the balanced equation above,

1 mole of CuO reacted with 1 mole of H2.

Therefore, 0.6 mole of CuO will also react with 0.6 mole of H2.

Finally, we shall determine the volume occupied by 0.6 mole of H2 at STP.

This can be obtained as follow:

1 mole of H2 occupied 22.4 dm³ at STP.

Therefore, 0.6 mole of H2 will occupy = 0.6 × 22.4 = 13.44 dm³.

Therefore, 13.44 dm³ of H2 is needed for the reaction.

4 0
3 years ago
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