Answer: The result is presented in proportion which gives a clearer understanding and accurate result.
Explanation: Percentage change in mass is the proportion of the initial mass of a substance changed after sometime. The results is presented as a percentage making it more accurate and can help to give future reference to weight calculations.
Change is Mass is the mass of a substance left after sometime mostly given in grams. It is not as accurate as percentage change in mass. It is generally better to show results in percentage change in mass as it gives a better understanding of what mass of a substance was lost after a given period or after application of energy like Heat or increased temperature.
Answer:
8.625 grams of a 150 g sample of Thorium-234 would be left after 120.5 days
Explanation:
The nuclear half life represents the time taken for the initial amount of sample to reduce into half of its mass.
We have given that the half life of thorium-234 is 24.1 days. Then it takes 24.1 days for a Thorium-234 sample to reduced to half of its initial amount.
Initial amount of Thorium-234 available as per the question is 150 grams
So now we start with 150 grams of Thorium-234





So after 120.5 days the amount of sample that remains is 8.625g
In simpler way , we can use the below formula to find the sample left

Where
is the initial sample amount
n = the number of half-lives that pass in a given period of time.
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<span>-Boron (B)
-Silicon (Si)
-Germanium (Ge)
-Arsenic (As)
-Antimony (Sb)
-Tellurium (Te)
-Polonium (Po)
<span>-Astatine (At)</span></span>
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
Answer:
Number of Na ions in 14.5 g of NaCl is 1.49 × 10²³.
Number of Cl ions in 14.5 g of NaCl is 1.49 × 10²³.
Total number of ions = 1.49 × 10²³ + 1.49 × 10²³ = 2.98 × 10²³.
Explanation:
1 mole of any compound contains 6.023 × 10²³ molecules.
molecular weight of NaCl is 23 + 35.5 = 58.5 g.
so, 58.5 grams of NaCl makes 1 mole
⇒ 14.5 g of NaCl =
= 0.248 moles.
⇒ 0.248 mole contains 0.248 × 6.023×10²³ molecules
= 1.49 × 10²³ molecules.
And 1 molecule contains 1 Na ion and 1 Cl ion.
⇒ number of Na ions in 14.5 g of NaCl is 1.49 × 10²³.
⇒ number of Cl ions in 14.5 g of NaCl is 1.49 × 10²³.
Total number of ions = 1.49 × 10²³ + 1.49 × 10²³ = 2.98 × 10²³.