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Virty [35]
2 years ago
13

Which of the following is an example of a model?

Chemistry
2 answers:
Ivanshal [37]2 years ago
8 0

Answer:

U

Explanation:

UUUUUUUUUUUUUU

777dan777 [17]2 years ago
5 0
Is there an image you can show?
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Can anyone help me on this please?
Bad White [126]
This question is testing to see how well you understand the "half-life" of radioactive elements, and how well you can manipulate and dance around them.  This is not an easy question.

The idea is that the "half-life" is a certain amount of time.  It's the time it takes for 'half' of the atoms in any sample of that particular unstable element to 'decay' ... their nuclei die, fall apart, and turn into nuclei of other elements.

Look over the table.  There are 4,500 atoms of this radioactive substance when the time is 12,000 seconds, and there are 2,250 atoms of it left when the time is ' y ' seconds.  Gosh ... 2,250 is exactly half of 4,500 !  So the length of time from 12,000 seconds until ' y ' is the half life of this substance !  But how can we find the length of the half-life ? ? ?

Maybe we can figure it out from other information in the table !

Here's what I found:

Do you see the time when there were 3,600 atoms of it ? 
That's 20,000 seconds.

... After one half-life, there were 1,800 atoms left.
... After another half-life, there were 900 atoms left.
... After another half-life, there were 450 atoms left. 

==>  450 is in the table !  That's at 95,000 seconds.

So the length of time from 20,000 seconds until 95,000 seconds
is three half-lifes.

The length of time is (95,000 - 20,000) = 75,000 sec

                                     3 half lifes = 75,000 sec

Divide each side by 3 :   1 half life = 25,000 seconds

There it is !  THAT's the number we need.  We can answer the question now.

==> 2,250 atoms is half of 4,500 atoms.

==> ' y ' is one half-life later than 12,000 seconds

==> ' y ' = 12,000 + 25,000

         y   = 37,000 seconds  .

Check: 
Look how nicely 37,000sec fits in between 20,000 and 60,000 in the table.

As I said earlier, this is not the simplest half-life problem I've seen.
You really have to know what you're doing on this one.  You can't
bluff through it.


7 0
3 years ago
Some scientists hypothesize that Earth's ozone layer is being damaged by
Amanda [17]

Answer:

Some scientists hypothesize that Earth's ozone layer is being damaged by chlorofluorocarbons .

Explanation:

Please mark brainliest and have a great day!

6 0
2 years ago
Read 2 more answers
There are well over 100 __________________ that exist on Earth
Nezavi [6.7K]

Answer:

species like plants, animals , human etc

7 0
3 years ago
Read 2 more answers
There are ___ atoms of oxygen in 300 molecules of CH3CO2H a) 300 b) 600 c) 150 d) 3.6 x 10^36
Maurinko [17]

<u>Answer:</u> The correct option is b) 600

<u>Explanation:</u>

Molecules are formed when two atoms of same or different elements combine together.

Atoms are the smallest unit of matter that combines to form a compound.

For the given chemical compound, CH_3CO_2H

Given number of molecules = 300 molecules

In 1 mole of the given chemical compound, there are 2 atoms of carbon, 4 atoms of hydrogen and 2 atoms of oxygen

Number of atoms of oxygen = 2\times \text{Number of molecules of compound}

Number of atoms of oxygen = 2\times 300=600atoms

Hence, the correct option is b) 600

8 0
3 years ago
Whats the answer will mark brainliest
DanielleElmas [232]

Explanation:

sorry the words are not visible, please take the photo again

6 0
3 years ago
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