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
Tanzania [10]
3 years ago
9

How did oxygen come up to make 21% of the earth's present atmosphere?

Chemistry
1 answer:
MakcuM [25]3 years ago
4 0
Tiny organisms known as cyanobacteria, or blue-green algae.
You might be interested in
Consider the nuclear equation below. 239/94 Pu—-> X+ 4/2 He. What is X?
Anna007 [38]

Answer:

X = U (Uranium)

Explanation:

Pu-->235/92 U + 4/2 He

4 0
3 years ago
Read 2 more answers
Explain three factors that can affect the size of a line in a spectrum.
Sunny_sXe [5.5K]

Answer:For atoms and molecules, the width of spectral lines is governed mainly by the broadening of the energy levels of the atoms or molecules during interactions with surrounding particles and by the broadening of the spectral lines as a result of the Doppler effect.

Explanation:

7 0
3 years ago
2. What mass of water absorbs 6700 J of heat to raise the temperature from 283K to 318K?​
Alexxandr [17]

Answer:

Q = mcT ...you can either substitute the molar heat capacity of water in the place of c or the specific heat capacity of water.

Explanation:

7 0
3 years ago
As the amount of salt in water increases, the___________ of the water increases.
Gnom [1K]

Answer:

3

Explanation:

5 0
3 years ago
Read 2 more answers
Place the following in order of increasing X-Se-X bond angle, where X represents the outer atoms in each molecule. SeO2 SeCl6 Se
GalinKa [24]

Answer:

SeCl₆ < SeF₂ < SeO₂

Explanation:

(A) SeO₂

The central atom has 2 bond pairs and 1 lone pair. The molecule is bent shaped which has an angle of 120°.

(B) SeCl₆

The central atom has 6 bond pairs and 0 lone pair. The geometry is octahedral in which the equatorial bonds has an angle of 90° and axial bond has an angle of 90°.

(C) SeF₂

The central atom has 2 bond pairs and 2 lone pairs. The geometry is bent shape which has an angle of approximately 105.5°.

The order is:

<u>SeCl₆ < SeF₂ < SeO₂</u>

5 0
3 years ago
Other questions:
  • Under which category will you classify Maple syrup ?
    7·1 answer
  • NEED HELP ASAP PLEASE
    9·2 answers
  • Compounds A and B react to form compounds C and D according to the equation: aA + bB → cC + dD. Under which conditions will the
    9·2 answers
  • What changes would occur at a molecular level if a liquid is placed in cool conditions?
    15·1 answer
  • If a cloud holding the most water vapor it possibly can suddenly cools what will occur
    7·2 answers
  • The standard temperature and pressure of gases are OK and 1 atm, respectively. (T/F)
    14·1 answer
  • 4. Diffuse reflection occurs when parallel light waves strike which surface?
    15·2 answers
  • For the reaction represented by the equation 2H2 + O2→ 2H2O, how many grams of water can be produced from 6.0 grams of O2?
    10·1 answer
  • Mass x height x gravity is the formula to calculate:
    7·1 answer
  • 7th grade science , help me please :))
    8·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!