What is significant about the temperature -40°C?
A. It's the temperature at which Fahrenheit and Celsius
thermometers read the same.
B. It's the temperature at which Kelvin and Celsius thermometers
read the same.
C. It's the boiling point of mercury.
D. It's absolute zero.

A. It's the temperature at which Fahrenheit and Celsius

thermometers read the same.

i believe the answer is true.

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.