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lawyer [7]
2 years ago
7

Umm care to help, please

Chemistry
2 answers:
marysya [2.9K]2 years ago
4 0

Answer:

17.5

Explanation:

Archy [21]2 years ago
3 0

20

Explanation:

Protons (the atomic number) and neutrons both contribute to the atomic mass.

If you therefore subtract the number of protons (19) from the atomic mass (39), you are left with the number of neutrons (=20).

hope this helped :)

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If an object has a Mass of 11g and a volume fo 13mil, what is its density?
Nimfa-mama [501]

Answer:

\boxed {\boxed {\sf B. \ d \approx 0.85 \ g/mL}}

Explanation:

Density is found by dividing the mass by the volume.

d=\frac{m}{v}

The mass of the object is 11 grams and the volume is 13 milliliters.

m= 11 \ g \\v= 13 \ mL

Substitute the values into the formula.

d= \frac{11 \ g}{13 \ mL}

Divide.

d=0.846153846 \ g/mL

Round to the nearest hundredth. The 6 in the thousandth place tells us to round the 4 to a 5.

d \approx 0.85 \ g/mL

The density is about <u>0.85 grams per milliliter.</u>

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2 years ago
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mrs_skeptik [129]

Answer:

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Explanation:

To find the amount of molecules, you need to multiply the number of moles by Avogadro's Number. Avogadro's Number is a ratio which represents the amount of molecules per every 1 mole. It is important to arrange this ratio in a way that allows for the cancellation of units (since you are going from moles to molecules, moles should be in the denominator). The final answer should have 3 sig figs like the given value.

Avogadro's Number:

6.022 x 10²³ molecules = 1 mole

 20.2 moles CO₂           6.022 x 10²³ molecules
---------------------------  x  --------------------------------------  = 1.22 x 10²⁵ molecules
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