Study the timeline. A timeline. 4.5 billion years ago, Earth is formed. 4.3 billion years ago, Earliest water. 4.1 billion years ago, Single celled life. 3.5 billion years ago, Earliest oxygen and photosynthesis. 2.5 billion years ago, Complex single celled life. 1.5 billion years ago, Multi cellular life. 500 million years ago, Land life. 300 million years ago, Dinosaurs. 200 million years ago, Mammals. 130 million years ago, Flowers. 5 million years ago, Humans.

Based on fossil evidence, about how long ago did the first single-celled life form appear on Earth?

130 million years ago
1.5 billion years ago
2.5 billion years ago
4.1 billion years ago
ITS 4.1 BILLION YEARS AGO!

The correct answer is - 4.1 billion years ago.

Explanation:

In the question, there is a timeline given based on the fossils evidence and on the base of this timeline, it is given that the earth formed around 4.5 Billion years ago. Soon after the earliest water, the first living unicellular single-celled organism found which is dated around 4.1 billion years ago.

It has appeared soon after the earth formed itself and after a billion years later the first photosynthetic organism occurred.

the sun d the answer is sun

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.