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svetoff [14.1K]
3 years ago
7

hardened remains of ancient plants and animals found in rocks are __________. a) crystals b) minerals c) fossils d) inorganic mo

lecules
Chemistry
1 answer:
Natalka [10]3 years ago
5 0
The answer would be C) fossils
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14.7 grams of magnesium reacts completely with 9.7 grams of oxygen to form magnesium oxide (MgO). What is the percent compositio
swat32
The answer is 60.3% magnesium, 39.7% oxygen.
Solution:
The chemical equation for the reaction is 2 Mg + O2 → 2 MgO.
Since magnesium reacts completely with oxygen, it is the limiting reactant in the reaction. Hence, we can use the number of moles of magnesium to get the mass of MgO produced:
     moles of magnesium = 14.7g / 24.305g mol-1
                                       = 0.6048 mol

     mass of MgO = 0.6048mol Mg(2 mol MgO/2mol Mg)(40.3044g MgO/1 mol MgO) 
                           = 24.376g MgO

We can now solve for the percentage of magnesium:
     % Mg = (14.7g Mg / 24.376g MgO)*100% = 60.3%

We also use the number of moles of magnesium to get the mass of oxygen consumed in the reaction:
     mass of O2 =  0.6048 mol Mg (1mol O2 / 2mol Mg) (31.998g / 1mol O2) 
                        = 9.676g

The percentage of oxygen is therefore
     % O2 = (9.676g O2 / 24.376g MgO)*100%
               = 39.7%
Notice that we can just subtract the magnesium's percentage from 100% to get 
     % O2 = 100% - 60.3% = 39.7%
5 0
3 years ago
24. Which Portuguese explorer sailed around Africa and across the Indian Ocean to reach India?
Sliva [168]

Answer:

Vasco de Gama

Explanation:

4 0
3 years ago
Read 2 more answers
What is a Newton?<br> explain please
Lina20 [59]

Answer:

it is the unit of Force

Explanation:

force is equal to Newton

5 0
3 years ago
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HELP O DONT UNDERSTAND THIS!IM SOOO STRESSED HOW DO I SOLVE IT
katrin [286]

Answer:

.86

.48

Explanation:

19/25 x 4/4 = 86/100

86/100 = .86

12/25 x 4/4 = 48/100

48/100 = .48

4 0
3 years ago
Fluoride is moderately basic, by far the most basic of the halides. It is a terrible leaving group. Fluoride is many orders of m
TEA [102]

Answer:   Bromide is many orders of magnitude better than fluoride in leaving group ability

Explanation:

As Size of an atom  Increases,  the Basicity Decreases this is because  if we move downwards  from the top of the periodic table to the bottom of the periodic table, the size of an atom increases. As size increases, basicity will decrease, meaning the element  will be less likely to act as a base implying that the element will be less likely to share its electrons.

in the same vein. With an increase in size, basicity decreases, making the ability of the leaving group to leave increase to increase . This can be seen in the halogens going down the group  from

F--- worst

Cl----fair

Br ----good

 I-----excellent

with fluorine having the worst ability to leave than Bromine which is better in terms of the leaving group ability.

3 0
3 years ago
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