The answer is D) a neutron.
When we say an atom's mass is, like 5 atomic mass units actually we are saying that the total number of the neutrons and protons in its nucleus is 5.
The mass of a neutron and a proton is each one atomic mass unit.
Mass of a neutron is approximately 1 atomic mass unit.
The density of the rectangular block in g/mL is 7.0.
<u>Given the following data:</u>
- Mass of block = 22.8 gra1.94 kg
- Length of block = 3.21 cm
- Height of block = 1.84 in.
To find the density of the block in g/mL:
First of all, we would determine the volume of the rectangular block by using the following formula:
×
× 
<u>Conversion:</u>
1 in = 2.54 cm
5.83 in = X cm
Cross-multiplying, we have:

×
× 
Volume = 277.16 cubic centimeters.
<u>Note</u>: Milliliter (mL) is the same as cubic centimeters.
1000 grams = 1 kg
Y grams = 1.94 kg
Cross-multiplying, we have:
Y = 1940 grams
Now, we can find the density:

<em>Density </em><em>= 7</em><em>.0 g/mL</em>
Therefore, the density of the rectangular block in g/mL is 7.0.
Read more: brainly.com/question/18320053
The change in energy of the system : -63 J
<h3>Further explanation</h3>
Given
279 J work
216 J heat
Required
The change in energy
Solution
Laws of thermodynamics 1
ΔU=Q+W
Rules :
- receives heat, Q +
- releases heat, Q -
- work is done by a system, W -
- work is done on a system, W +
a gas work on the surrounding : W =-279 J
a gas absorb heat from surrounding : Q = +216 J
Internal energy :
= -279+216
= -63 J
Hey there! Hello!
Not sure if you still need the answer to this question, but I'd love to help out if you do.
So, the way to balance this equation is pretty simple. First, you need to keep in mind that molecules of hydrogen and oxygen do not come in single molecules, but in bonded pairs, represented by H2 and O2.

But, that's incorrect. The combination of 2 hydrogen molecules with 1 oxygen molecule yields water, but that leaves one oxygen molecule leftover. When broken down, this is how many of each molecule is on each side of the previously stated equation:
Left:
H: 2
O: 2
Right:
H: 2
O: 1
So we have to multiply H2O on the right side by 2 in order to get this:

Left:
H: 2
O: 2
Right:
H: 4
O: 2
The last step is to multiply H2 on the left by two to make it match up with the right side, balancing the equation:

Left:
H: 4
O: 2
Right:
H: 4
O: 2
That makes our equation balanced! I hope this helped you out, feel free to ask any additional questions if you need further clarification. :-)