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arlik [135]
3 years ago
7

How old are the oldest fossils on earth?

Chemistry
2 answers:
blondinia [14]3 years ago
5 0

the oldest fossils on earth are 3.5 billion years

sertanlavr [38]3 years ago
4 0

Over 3.5 billion years old! Hope this helps :)

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How many calories is required to change the temperature of 2.18g of water from 15.3°C to 69.5°C. The specific heat of liquid wat
lozanna [386]

The number  of calories that are  required  to change the temperature  of 2.18 g of water from 15.3 c to 69.5 c is  <u>118.16 cal</u>


    <u><em> calculation</em></u>

  •    Heat in calories  = MCΔ T where,
  • M(mass)= 2.18 g
  • C(specific heat capacity)= 1.00 cal/g/c
  • ΔT( change in temperature)= 69.5- 15.3 =54.2 c

 heat is therefore= 2.18 g x 1.00 cal/g/c  x 54.2 c=118.16  cal

7 0
3 years ago
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What is the speed of a car that has traveled 100 miles in 20 hours?<br> |
77julia77 [94]

Answer:

5 mph

Explanation:

100 miles, 20 hours (divide by 2)

50 miles,    10 hours (divide by 2)

25 miles,    5 hours (divide by 2)

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3 0
3 years ago
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An unknown compound displays singlets at δ 2.1 ppm and 2.56 ppm in the ratio of 3:2. what is the structure of the compound?
olasank [31]

1) As can be seen from any 1H NMR chemical shift ppm tables, hydrogens which have δ values from 2ppm to 2.3ppm are hydrogens from carbon which is bonded to a carbonyl group. From this, we can conclude that our hydrogens belong to the type, but from 2 different alkyl groups because of 2 different signals.

 

2) So, one alkyl group is CH3 and second one can be CH or CH2.

 

3) If we know that ratio between two types of hydrogens is 3:2, it can be concluded that second alkyl group is CH2. 


4) Finally, we don't have any other signals and it indicates that part of the compound which continues on CH2 is exactly the same as the first part.

The ratio remains the same, 3:2 ie 6:4

7 0
3 years ago
.<br> How many moles are there in 8.5 x 1024 molecules of sodium sulfate, Na2SO4?
NeTakaya

Answer: To solve this question, we need to use the Avogadro's Number, which is a constant first discovered by Amadeo Avogadro, an Italian scientist. He discovered that in a mole of a substance, there are 6,02*10²³ molecules. Using this relationship, we apply the following conversion factor:

So, 8,50 * 10²⁴ molecules of Na₂SO₃ represent 14,12 moles of Na₂SO₃

Explanation:

5 0
3 years ago
Which contains 3 significant figures.
jolli1 [7]
B, E, F have 3 significant figures
4 0
3 years ago
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