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jarptica [38.1K]
3 years ago
14

What event marks the beginning of Earth's current era?

Chemistry
2 answers:
Firlakuza [10]3 years ago
4 0
It’s B a mass extinction

uysha [10]3 years ago
3 0
B. We are in the cenzoic era so what previously had happen to cause the life we live today was a huge mass extinction.... hope this helps!!
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What would be the approximate size in cubic cm of just 1 atom?
Triss [41]
6*10^-20 cm^3 I think
8 0
3 years ago
Convert 45 joules to heat calories
skad [1K]

Answer:

45 joules to calories= 10 (10.755258) calories

3 0
4 years ago
Order the steps required to extract a dichloromethane solution with aqueous hydrochloric acid.
ch4aika [34]

The formatting of the question is a bit scrambled: I'm not sure if there are separate steps that have been unintentionally consolidated into a seemingly discrete step, nor am I sure which letters actually correspond with which step(s). So, for clarity's sake, I treated every sentence as its own step and arranged all of them accordingly. Hopefully, you can then reorganize them according to the labeled steps as you have been provided.

  1. Suspend a separatory funnel using an iron ring and ring stand.
  2. Make sure the stopcock is closed.
  3. Transfer the organic (dichloromethane) layer to the funnel.
  4. Add an equivalent volume of aqueous acid to the dichloromethane layer in the separatory funnel.
  5. Cap the separatory funnel with a glass or Teflon stopper.
  6. Remove the funnel from the iron ring and shake vigorously to mix the layers, periodically venting to release pressure.  
  7. Place the separatory funnel back in the Iron ring.
  8. Allow the layers to physically separate in the funnel.
  9. Remove the cap.
  10. Drain the bottom layer into a labeled beaker.
  11. Label the beaker "Organic Layer".
  12. Drain the remaining liquid into a labeled beaker.  
  13. Label this beaker "Aqueous Layer".
  14. Transfer the "Organic Layer" back to the empty separatory funnel.
  15. Repeat all steps.

Notes:

  • The letters have been replaced with numbers only to clarify the order of the steps. No changes were made to the steps themselves, including any stylistic errors.
  • A <em>very few</em> set of sequential steps might be interchangeable, but the steps as separated and organized above is in accordance with standard liquid-liquid extraction protocol.
  • Determining which layers are the "organic" and "aqueous" layers (i.e., whether the organic/aqueous layer, or vice-versa, is on the bottom/top ) is a nontrivial step; for this reason, when actually doing such extractions, the beakers (or whatever vessel) into which the layers are drained at any step are sometimes labeled "top layer" and "bottom layer" in case you misidentify which layers are, in fact, the organic and aqueous layers. Oftentimes, the organic layer is on top of the aqueous layer as many common organic solvents are less dense than water. Halogenated organic solvents, like dichloromethane, are one of the exceptions, and so will generally comprise the bottom layer.
7 0
3 years ago
An atom has 17 protons and 18 neutrons.
eimsori [14]

Answer:

35Cl

Explanation:

The number of protons in an element is it's atomic number. Atomic number of Cl is 17. So the element is chlorine. The total sum of the number of protons and neutrons gives the mass number.So mass number of Cl is 17+18=35.So the given atom is Chlorine with mass number

35.

5 0
3 years ago
You are given a clear solution of KNO3. Using 3-4 sentences explain how you would determine if the solution is unsaturated,satur
Natasha2012 [34]
Without being given a temperature or amount of solute, it's not as easy to find the level of saturation. If there is excess of solvent in the beaker, the solution is unsaturated. In this case, the solution is clear so there is no indication of excess of solute or solvent. Therefore, the solution is saturated.
6 0
3 years ago
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