Pls help and Thx!! What is considered an object's half-life?

There are specialized producers that live in warm water vents deep in the ocean. these producers do not per-form from photosynthesis, but instead perform a similar process with iron and other chemicals. why do you think these producers use this process instead of photosynthesis?

1. emigration the movement of people from one place to another 2. immigration a situation in which resources are being used up at a faster rate than they can be replenished 3. migration the leaving of one's homeland to settle in a new place 4. overpopulation the movement of people to a new country 5. sustainable development a situation in which the birth rate is not sufficient to replace the existing population 6. underpopulation the ability to meet current needs without reducing the ability to meet future needs 7. unsustainable development the increase in the population of a city 8. urbanization a situation in which the number of people exceeds the available natural resources in an area

Plz ! having a smooth seeds is the dominant trait. having wrinkled seeds is a recessive trait. the offspring of two plants with smooth seeds, a. must have smooth seeds. b. may have smooth or wrinkled seeds. c. must have wrinkled seeds. d. have a 25% change of having smooth seeds.