Which step will decrease the pressure of a gas inside a closed cubical container? increasing the number of moles of gas
decreasing the volume of the container
increasing the speed of the gas particles
decreasing the temperature inside the container

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.

the right answer is c i just did the question.

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.