The correct options are, frying an egg and burning candle.
Explanation :
Physical change : It is a change in which no new compounds are formed only changes occurs in size or state of substance. In this, there is no changes in the substance or compound.
Chemical change : It is a change in which a new compounds are formed by the chemical reaction. Changes occurs in their chemical composition and properties.
Frying an egg : It is a chemical change because a new substance is form by heating.
Burning a candle : It is chemical change because new substances are formed (carbon dioxide, water and heat) by burning.
Boiling alcohol : It is physical change because only changes in the state.
Melting and ice : It is a physical change because only changes in the state.
Making coffee : It is a physical change because no new substance is formed.
Therefore, frying an egg and burning candle are the example of chemical change.
Answer:
Oxygen levels stay above 15 percent starting 200 million years ago
Explanation:
Atmospheric oxygen levels are related to the evolution on Earth and changes in geochemical cycles that involve climate variations.
The presence of O
2 and evolution of oxygen gave new opportunities to the life on Earth. Oxygen levels in atmosphere have fluctuated between 15% and 35% of atmospheric volume, since the start of the Cambrian period.
So, form the starting 200 million years ago, oxygen level stay above 15 percent and the correct option is "B".
Answer: Photosynthesis is process of green plants and organisms use sun or UV light to <u>synthesize </u>from CO2 (carbon dioxide) and water to make food. Usually producing green pigment called chlorophyll (what makes leaves green) and oxygen as a byproduct which they do not need.
