A student went outside every night for eight nights to look at the Moon. The pictures below show how the Moon looked each

o-na [289]

Answer:

C the number and placement of the electrons

Explanation:

Elements react with one another because they want to achieve a full valence shell of electrons. The noble gases already have a full valence shell of electrons, so they are unlikely to react with other elements.

6 0

2 years ago

How many g of MgCO3(s) are needed to make 1.2 L of 1.5 M MgCl2(aq) solution?

maw [93]

Molar mass of MgCO3 is 84.313 g/mol
You can calculate this from data on the periodic table:
Molar mass Mg = 24.305g/mol
molar mass C = 12.011g/mol
molar mass O = 15.999g/mol mass 3 mol = 47.997g
Total = 84.313g/mol

Mass to be used in 1.2L of 1.5M solution = 84.313g * 1.2L * 1.5mol /L = 151.763g
I have not taken significant figures into account
The balanced equation you provide is not necessary in this calculation

4 0

2 years ago

What animal is most like to harmed when a beaver builds a dam

siniylev [52]

Answer:

Small fish or insects.

Explanation:

3 0

3 years ago

Read 2 more answers

HELP ME PLSSSSS THIS TEST IS TIMED!!!! Write a conclusion statement that addresses the following questions: • How did your exper

SVETLANKA909090 [29]

Although the data for the experiment was not provided, we can offer a generalized answer in that when performing an experiment to achieve absolute zero temperatures, the value will never match the exact value.

<h3 /><h3>What is absolute zero?</h3>

Absolute zero is the lower limit of temperature. It is considered the coldest possible temperature that can exist. However, any attempt to reach this temperature in a controlled environment has failed, <u>scientists do not think it is possible to recreate this </u><u>temperature</u><u>. </u>

Therefore, we can confirm that the value of the absolute zero experiments did not match the accepted value. If the hypothesis was that it would be difficult or impossible to achieve, then the data would support the hypothesis, otherwise, it would fail to do so.

In summary, absolute zero is a temperature that cannot be recreated in a lab, so the value in this experiment does not match the accepted value and there is <u>no further exploration </u>to be done on this matter.

To learn more about absolute zero visit:

brainly.com/question/79835?referrer=searchResults

4 0

2 years ago

A sample of pure calcium fluoride with a mass of 15.0 g contains 7.70 g of calcium. how much calcium is contained in 45.0 g of c

kolbaska11 [484]

In a sample of pure calcium fluoride of mass 15.0 g, 7.70 g of calcium is present. First convert the mass into number of moles as follows:

$n=\frac{m}{M}$

Here, m is mass and M is molar mass.

Molar mass of Ca is 40 g/mol, putting the values,

$n=\frac{7.70 g}{40 g/mol}=0.1925 mol$

Similarly, molar mass of $CaF_{2}$ is 78.07 g/mol thus, number of moles will be:

$n=\frac{15.0 g}{78.07 g/mol}=0.1921 mol$ .

Thus, 0.1921 mol of $CaF_{2}$ have 0.1925 mol of Ca, or 1 mole of $CaF_{2}$ will have approximately 1 mole of Ca.

Now, mass of Ca needs to be calculated in 45.0 g of $CaF_{2}$ . Converting mass into number of moles first,

$n=\frac{45.0 g}{78.07 g/mol}=0.5764 mol$

Thus, number of moles of Ca will also be 0.5764 mol, converting number of moles into mass,

$m=n\times M=0.5764 mol\times 40 g/mol=23.06 g$

Therefore, mass of Ca will be 23.06 g.

6 0

3 years ago