A scientist heats an unknown substance in a closed system. The graph shows the change in temperature over time.
E
D
B
Temperature
С
А
Time
How does the scientist know that the substance goes through a change of
state during the time period labeled B on the graph?

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so she was walking and she stepped on warm jeffy , uh uh uhh dadye i just pooped my pants

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.