A substance has a half-life of 100,000 years and an initial mass of 1,000 grams. How many years will pass before only 250 grams of the substance's parent material is left?

the core of the sun is so hot and there is so much pressure, nuclear fusion takes place, hydrogen is changed to helium. nuclear fusion creates heat and photons. when the heat reaches the earth it warms the molecules of the atmosphere, and they warm other molecules and so on.

a

explanation:

b. the carbon cycle ensures living things have a source of hydrogen

i'm guessing this is from edg enuity so the answers would be, from top to bottom,

theodor schwann

matthias schleiden

robert hooke

rudolph virchow

anton van leeuwenhoek