A rock sample has a half-life of 30 years, and it originally had 1,000g of radioactive material. After 90 years, how much of the original material is left?

Why are feelings effecting people now then

Melanocytes and keratinocytes work together in protecting the skin from uv damage when keratinocytes a. provide the melanocyte with a protective shield against abrasion b. maintain the appropriate temperature so the product of the melanocyte will not denature c. maintain the appropriate ph in order for the melanocyte to synthesize melanin granules d. accumulate the melanin granules on their superficial portion, forming a uv-blocking pigment layer

Which activity causes the greatest risk of driving fatalitiesa. driving at nightb.driving while distractedc.driving with a passengerd.driving on a clear day