What is the mass of Neptune? Someone helpppppp!!!!

Write the isotope notation for the following isotope: copper-63, copper-65, magnesium-24, magnesium-25, magnesium-26, lithium-6,

andrey2020 [161]

63/29 Cu (copper-63)
65/29 Cu (copper-65)
24/12 Mg (magnesium 24)
25/12 Mg (magnesium 25)
26/12 Mg (magnesium 26)
6/3 Li (lithium 6)
7/3 Li (lithium 7)

The top number is the mass number and you find that by adding the number of neutrons and atomic number
The bottom number is the atomic number and it’s the number or protons

3 0

3 years ago

What is the composition, in atom percent, of an alloy that consists of a) 5.5 wt% Pb and b) 94.5 wt% of Sn? Assume that the atom

Anastaziya [24]

Answer : The percent composition of Pb and Sn in atom is, 3.21 % and 96.8 % respectively.

Explanation :

First we have to calculate the number of atoms in 5.5 wt% Pb and 94.5 wt% of Sn.

As, 207.2 g of lead contains $6.022\times 10^{23}$ atoms

So, 5.5 g of lead contains $\frac{5.5}{207.2}\times 6.022\times 10^{23}=1.59\times 10^{22}$ atoms

and,

As, 118.71 g of lead contains $6.022\times 10^{23}$ atoms

So, 94.5 g of lead contains $\frac{94.5}{118.71}\times 6.022\times 10^{23}=4.79\times 10^{23}$ atoms

Now we have to calculate the percent composition of Pb and Sn in atom.

$\% \text{Composition of Pb}=\frac{\text{Atoms of Pb}}{\text{Atoms of Pb}+\text{Atoms of Sn}}\times 100$

$\% \text{Composition of Pb}=\frac{1.59\times 10^{22}}{(1.59\times 10^{22})+(4.79\times 10^{23})}\times 100=3.21\%$

and,

$\% \text{Composition of Sn}=\frac{\text{Atoms of Sn}}{\text{Atoms of Pb}+\text{Atoms of Sn}}\times 100$

$\% \text{Composition of Sn}=\frac{4.79\times 10^{23}}{(1.59\times 10^{22})+(4.79\times 10^{23})}\times 100=96.8\%$

Thus, the percent composition of Pb and Sn in atom is, 3.21 % and 96.8 % respectively.

6 0

4 years ago

Which of the following are pure substances? (Select all that apply.)

riadik2000 [5.3K]

Elements and compounds are both examples of pure substances. Compounds are substances that are made up of more than one type of atom. Elements are the simplest substances made up of only one type of atom. i hope that helps:)

6 0

3 years ago

The temperature in a town started out at 55 degrees. By the end of the day the temperature dropped to -6 degrees.

garik1379 [7]

Answer:

The choice of the answer is fourth option that is -61 degrees.

Therefore the temperature drop is -61°Centigrade.

Explanation:

Given:

The temperature in a town started out at 55 degrees

Start temperature = 55°Centigrade. (Initial temperature)

End of the Day = -6°Centigrade. (Final temperature)

To Find:

How far did the temperature drop?

Solution:

We will have,

$\textrm{Temperature drop}=\textrm{Final temperature}-\textrm{Initial temperature}$

Substituting the above values in it we get

$\textrm{Temperature drop}=-6-55\\\\\therefore \textrm{Temperature drop}=-61\° centigrade$

Therefore the temperature drop is -61°Centigrade.

4 0

3 years ago

To describe the length of a classroom, a student should use

Kamila [148]

The answer is D).....

8 0

4 years ago

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