What is the current predicted doubling time for the world population?

a. d, 50 years

b. 19 years

c. 83 years

d. 40 years

The current predicted doubling time is 61years which makes 50years in your option the nearest possible answer.

Explanation:The world's current (overall as well as natural) growth rate is about 1.14%, representing a doubling time of 61 years.

We can expect the world's population of 6.5 billion to become 13 billion by 2067 if current growth continues.

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.