What is the change in atomic mass number when an atom emits an alpha particle?

decreases by 2

*decreases by 4

increases by 2

increases by 4

2.

If an isotope decays by the process of beta emission, ____.

the mass number changes

*the atomic number changes

protons are given off

the number of neutrons remains the same

3. 56 25Mn —> _____ + 0/-1e

56/27Co

27/56Mn

56/26Fe

58/24Cr

I don’t know this one.

4.

Which of the following naturally occurring radioisotopes would be most useful in dating objects thought to be millions of years old?

carbon-14; t1/2= 5.73 x 103 years

*potassium-40; t1/2= 1.28 x 109 years

thorium-234; t1/2= 25 days

radon-222; t1/2= 3.8 days

5.

The production of carbon-14 ____.

*takes place in the upper atmosphere

is mostly due to fallout from nuclear explosions

occurs to a large extent in nuclear reactors

is caused by photsynthesis in plants

Thank You.

3. 56 25Mn —> _____ + 0/-1e

56/27Co

27/56Mn

56/26Fe

58/24Cr

I don’t know this one.

I think it is easier to see if we separate the numbers. I will write that as 25Mn56 ==> -1e0 + X

The numbers to the left must add up on both sides. The numbers on the right do the same.

So 25 = -1 + what? Must be 26

Look on the periodic chart and you find 26 is Fe.

Then 56 = 0 + what? must bre 56. So X is

26Fe56.

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