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vitfil [10]
3 years ago
11

PLEASE HELP!!

Chemistry
2 answers:
ivann1987 [24]3 years ago
5 0
The half-life of a radioactive substance describes the amount of time required for half of that radioactive substance to decay into a different form.

In this situation, 100 grams decays into 12.5 grams over the course of 8 hours. We have half lives that look like this -

100 grams - 50 grams (1) - 25 grams (2) - 12.5 grams (3)

three half lives have passed since the start over the course of eight hours, so:

8 hours/3 half-lives = ~2.667 hours per half-life

The half-life of this substance is approximately 2.667 hours.

Hope this helps!
omeli [17]3 years ago
3 0

Answer:

8/3 hours

Explanation:

12.5/100=1/8, 1/8*2=2/8=1/4 1/4*2=1/2 1/2*2 = 1 (whole)

we multiplyed 1/8 by two three times to get 1 so 8/3 hours is the answer

by the way i'm in 6th grade

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How many moles of oxygen are present in 33.6l of the gas at 1atm and 0c
andreev551 [17]

The answer is: 1.5 moles of oxygen are present.

V(O₂) = 33.6 L; volume of oxygen.

p(O₂) = 1.0 atm; pressure of oxygen.

T = 0°C; temperature.

Vm = 22.4 L/mol; molar volume at STP (Standard Temperature and Pressure).

At STP one mole of gas occupies 22.4 liters of volume.

n(O₂) = V(O₂) ÷ Vm.

n(O₂) = 33.6 L ÷ 22.4 L/mol.

n(O₂) = 1.50 mol; amount of oxygen.

5 0
3 years ago
Select the term that best completes the following statement:
ankoles [38]

Answer:

C. oxygen atom

Explanation:

H2O contains two hydrogen atoms and one oxygen atom.

3 0
3 years ago
Why does naphthalene have a higher melting point than biphenyl?
AlexFokin [52]

<span>Naphthalene has a higher melting point than biphenyl because naphthalene is a polar compound while biphenyl is a non-polar compound.</span> Studies show <span>that polar compounds have higher melting and boiling points than nonpolar compounds. It is because polar compounds have strong intermolecular forces.</span>

4 0
3 years ago
Determine the pH of an HNO2 solution of each of the following concentrations:
Zepler [3.9K]

Answer:

i think that the answer is B

Explanation:

I DON

5 0
3 years ago
If the potato solution was boiled for 10 minutes and cooled for 10 minutes before being tested, the average time for the disks t
igor_vitrenko [27]

Answer:

Option D: More than 30 seconds

Explanation:

The enzyme CATALASE is found in almost all living organisms. CATALASE helps in the decomposition of one substance into another substance. CATALASE will breaks down hydrogen peroxide into water and oxygen.

When the potatoes were boiled it will surely produce no bubbles because the heat would have degrade the enzyme - catalase While the potatoes at room temperature potato produced the most bubbles because catalase works best at a room temperature.

If the potato solution was boiled for 10 minutes and cooled for 10 minutes before being tested, the average time for the disks to float to the surface of the hydrogen peroxide solution would be MORE THAN 30 SECONDS

5 0
3 years ago
Read 2 more answers
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