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dexar [7]
3 years ago
10

There's a 50 gram sample of our Ra-229 it is half-life is 4 minutes how much will be left after 12 minutes

Chemistry
1 answer:
KIM [24]3 years ago
7 0

The half life of an isotope is the amount of time it will take for the given isotope to decay till the point where it reaches half of what amount you had started with.

If the half life of Ra-229 is 4 minutes then every 4 minutes the sample is reduced to half of what you had before

4 minutes.)     50/2 Ra-229 --> 25g Ra-229

8 minutes.)     25/2 Ra-229 --> 12.5 Ra-229

12 minutes.)    12.5/2 Ra-229 --> 6.25 Ra-229 remaining

<em>I beleive this is the correct answer</em>

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The atomic number of Re is 75. The atomic mass of one of its isotopes is 186. How many neutrons are in an atom of this isotope?
USPshnik [31]

Answer:

B.111

Explanation:

Atomic mass = number of protons(or atomic number) + number of neutrons

186 = 75 + number of neutrons

number of neutrons = 186 -75 = 111

7 0
3 years ago
A. what is atmospheric pressure?
Vanyuwa [196]

Answer:

<em>What is atmospheric pressure? -------> Atmospheric pressure is a force in an area pushed against a surface by the weight of the atmosphere of Earth, a layer of air.</em>

<em>Why does the atmosphere exert pressure? -------> Because gas particles in the air—like particles of all fluids—are constantly moving and bumping into things, so they exert pressure. </em>

<em>What is the value of atmospheric pressure at sea level, in newtons per square centimeter? -------> Atmospheric pressure at sea level is about 10 N/cm2 or 100 kPa or about 10 m of water or about 760 mm of mercury, but varies with the weather, and of course altitude.</em>

<em>I hope this helps and have a great day!</em>

Explanation:

6 0
3 years ago
The metals in Groups 1A, 2A, and 3A ____.
Ket [755]
The correct answer is D.


I hope that helped! c:
6 0
3 years ago
(2k-1)²<br> what the answer pls.​
Sedaia [141]

Answer:

4k^2-4k+1

Explanation:

Plx give brainlyest

7 0
2 years ago
17. Which of the following is NOT an empirical formula? *
Aloiza [94]

Answer: 17) d. C_2H_6

18. c. The empirical formula of a compound can be twice the molecular formula.

Explanation:

Molecular formula is the chemical formula which depicts the actual number of atoms of each element present in the compound.  

Empirical formula is the simplest chemical formula which depicts the whole number of atoms of each element present in the compound.  

To calculate the molecular formula, we need to find the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

n=\frac{\text{molecular mass}}{\text{empirical mass}}

The empirical mass can be calculated from empirical formula and molar mass must be known.

17. Thus the empirical formula of C_2H_6 should be CH_3

18. The molecular formula will either be same as empirical formula or is a whole number multiple of empirical formula. Thus the empirical formula of a compound can never be twice the molecular formula.

3 0
3 years ago
Read 2 more answers
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