1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
inessss [21]
3 years ago
6

When did oxygen first appear in earth's atmosphere??

Chemistry
1 answer:
ad-work [718]3 years ago
7 0
<span> the atmosphere holds about 21 per cent oxygen. Over the Earth’s 4.6 billion year history, oxygen did not appear in the atmosphere until perhaps about 2.5 billion years ago. Since then, oxygen levels have fluctuated in tandem with global geological and biological events, such as mass extinctions.</span>
You might be interested in
Most substances can exist as a solid, liquid, or gas depending on ? ( science
earnstyle [38]

Answer:

The amount of energy in molecules of matter determines the state of matter.

Explanation:

The amount of energy in molecules of matter determines the state of matter. Matter can exist in one of several different states, including gas, liquid, or solid-state.

3 0
3 years ago
Read 2 more answers
What do you need to do to get larger sugar crystals? ​
Brilliant_brown [7]
Let the solution cool down really slowly, don’t disturb it at all.
5 0
3 years ago
The figure above shows the electric field around a positive charge. Where is the field strongest
WINSTONCH [101]
The electric field, or any field such as magnetic field or gravitational field, is the strongest the closer we get to the source of the field. The concentration of field lines also increases closer to the object; these field lines are seen to be coming out of a positive charge. 
Therefore, the strongest electric field is at the point where the concentration of electric field lines is the highest.
4 0
3 years ago
Kinetic energy <br><br>definition:<br><br><br>sentence: ​
Irina18 [472]

Answer:

Kinetic energy , is the energy of an object possessed due to it's motion

Explanation:

Kinetic energy is the energy of mass in motion. The kinetic energy of an object is the energy it has because of its motion.

it's formula ½mv²

7 0
3 years ago
Explain, in terms of electrons, why the bonding in strontium sulfide, SrS, is similar to the bonding in magnesium bromide, MgBr2
Aleksandr-060686 [28]

Answer: both compounds have ionic bond between metal and non-metal

Explanation: both Sr and Mg are earth alkaline metals and form ions Mg^2+

And Sr^2+. Br forms ion Br^- and S ion is S^2+.

5 0
3 years ago
Other questions:
  • The tendency of an object to resist change in its motion
    15·2 answers
  • According to the ph scale, which substance is the most basic?
    6·1 answer
  • The ___ is the short form that chemists use to identify an element
    7·1 answer
  • Scientists often organize data by constructing a graph what does a graph help scientists do?
    6·2 answers
  • Anybody know the answer from least to most electronegative atom?
    12·1 answer
  • In condensation reactions, the atoms th make up a water from what?
    11·1 answer
  • How many atoms in a 40 L sample of Ne?
    7·1 answer
  • Name the chemical bond present in sodium chloride Nitrogen gas and carbon tetrachloride​
    12·1 answer
  • CaF2 + (NH4)2O --&gt; 2 NH4F + CaO How many grams of NH4F can be formed from 34.6 grams of CaF2? (AKS 4f)
    15·1 answer
  • I REALLY NEED THE HELP
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!