Answer:
One of the errors for low percentage of magnesium could be because not all the magnesium may have reacted.
Explanation:
During the heating process, if the magnesium have not reacted completely, it can lead to low percentage of magnesium in the oxide formed. The product may still look a bit greyish rather than whitish after the heating process.
Explanation:
It is known that one mole of chromium or molar mass of chromium is 51.99 g/mol.
It is given that number of moles is 11.9 moles.
Therefore, calculate the mass of chromium in grams as follows.
No. of moles = 
mass in grams = No. of moles × Molar mass
= 11.9 moles × 51.99 g/mol
= 618.68 g
Thus, we can conclude that there are 618.68 g in 11.9 moles of chromium.
Taking into account the definition of avogadro's number, 3.37×10⁻⁷ moles of methane are 20.32×10¹⁶ molecules.
First of all, you have to know that Avogadro's number indicates the number of particles of a substance (usually atoms or molecules) that are in a mole.
Its value is 6.023×10²³ particles per mole and it applies to any substance.
Then you can apply the following rule of three: if 6.023×10²³ molecules are contained in 1 mole of methane, then 20.32×10¹⁶ molecules are contained in how many moles of methane?
amount of moles of methane= (20.32×10¹⁶ molecules × 1 mole)÷ 6.023×10²³ atoms
Solving:
<u><em>amount of moles of methane= 3.37×10⁻⁷ moles</em></u>
Finally, 3.37×10⁻⁷ moles of methane are 20.32×10¹⁶ molecules.
Learn more about Avogadro's Number:
Answer:
B. decay of dead marine organisms
Explanation:
When the temperature is low, carbon dioxide is captured by the oceans, and when the temperature is high, it is released by the oceans into the atmosphere. At sea, carbon dioxide feeds phytoplankton.
Most of the carbon dioxide consumed by plant plankton (phytoplankton) returns to the atmosphere when this phytoplankton dies or is consumed, but a portion is deposited in the ocean floor sediments when these small particles sink. This process is called a "biological bomb" because carbon dioxide is transported from the atmosphere to the ocean floor.
