What is the correct answer with the appropriate significant digits?6.25 x 19.50

hey your not cool]      

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

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c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

the answer is 0.42 is that is an option. this question provides no info