Polonium-208 is an alpha emitter with a half-life of 2.90 years. how many milligrams of polonium from an original sample of 2.00 mg will remain after 8.00 years? a) 0.147 mg b) 0.296 mg c) 0.725 mg d) 6.77 mg e) 1.90 mg.

The answer to your question is letter B.

Explanation:

Data

Polonium-208 half-life = 2.9 years

Original sample = 2 mg

Total time = 8 years

Process

                     Mass                  Time

                     2 mg                 0 years

                     1 mg                   2.9 years

                      0.5 mg              5.8 years

                      0.25 mg            8.7 years

The mass of sample must be between 0.5 and 0.25 mg, from the options given the only possible answer is letter B 0.296 mg

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.