The mass number is the sum of the number of protons and number of neutrons the atom has.
So, we can write the equation as:
x + 20 = 40
x = 20 neutrons.
Answer:b) The air at high altitudes are less dense, so its harder to breathe.
Explanation:
AS altitude increases, the air pressure drops. This reduces the amount of gas molecules in the air so the air becomes less dense compared to air closer to sea level.
Complete question: You will find the complete question in the attached files, due to technical problems.
Answer and Explanation:
<u>Due to technical problems</u>, you will find the complete question, answer, and explanation in the attached files.
Answer:
3.5 billion years ago, or in the Eoarchean Era.
Explanation:
The first known single-celled organisms appeared on Earth about 3.5 billion years ago, roughly a billion years after Earth formed. More complex forms of life took longer to evolve, with the first multicellular animals not appearing until about 600 million years ago.
The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, during the Eoarchean Era.
Have a fantastic rest of your day!! \(^u^\)
False, I'd say. Mammals usually adapt based on environment. Now, I know predators are "apart" of the environment, but I don't think that'd be it. I'd bet more money on saying mammals evolve based on environment adaptation. Sorry if I didn't answer your question or if I didn't get my point across well.
