The Great Oxidation Event (GOE), sometimes also called the Great Oxygenation Event, Oxygen Catastrophe, Oxygen Crisis, Oxygen Holocaust,[2] or Oxygen Revolution, was a time period when the Earth's atmosphere and the shallow ocean first experienced a rise in oxygen, approximately 2.4 billion years ago (2.4 Ga) to 2.1–2.0 Ga during the Paleoproterozoic era.[3] Geological, isotopic, and chemical evidence suggests that biologically produced molecular oxygen (dioxygen, O2) started to accumulate in Earth's atmosphere and changed Earth's atmosphere from a weakly reducing atmosphere to an oxidizing atmosphere,[4] causing many existing species on Earth to die out.[5] The cyanobacteria producing the oxygen caused the event which enabled the subsequent development of multicellular forms.
Answer:
C. cooler than both the crust and the core
Explanation:
It is observed that at the mantle, temperatures range from estimatedly 200 °C (392 °F) around the upper boundary with the crust to approximately 4,000 °C (7,230 °F) at the core-mantle boundary.
So we can say the mantle is cooler than both the crust and the core.
Answer:
Explanation:
Here, we want to convert J to cal
Mathematically:
Thus, to get our answer in cal, we divide the value given by 4.186
We have that as:
Answer:
D
Explanation:
Firstly it is pertinent to know that, Electric force are due to the movement of electrons that is due to its gain and loss. This phenomenon is based on static electricity.
When the glass ruler is rubbed over the woolen sweater, the wool gets positively charged and the ruler gains electron to form negative charge.
Now if this charged is not earthed, the negative charged ruler attracts the uncharged bits of paper, as a result of which the paper gets attached to the ruler.
