Where do most Africans live?

Which of the following is not a place where hydrogen can be found on earth? a. natural gas well b. atmosphere c. water d. mine

Which of the following statements best characterizes changes to agriculture in the united states since 1900? a. increased mechanization has reduced the need for labor.b. increased mechanization has increased the need for water, thereby increasing the need for labor.increased mechanization has increased the use of land, thereby increasing the need for labor.d. increased mechanization has increased food production, thereby increasing the need for labor. select the best answer from the choices provided.

Given: circle a externally tangent to circle b. how many possible common tangents to circles a and b can exist? 2 3 4