Hi!
The correct option would be 3.85x10^(24)
To find the number of atoms in 250g of potassium, we need to first calculate the number of atoms in
1 mole of Potassium = 39g which contains 6.022x10^(23) atoms of K
<em>(Avogadro's constant value for the amount of molecules/atoms in one mole of any substance)</em>
<em>Solution</em>
So as 39g of Potassium contains 6.022x10^(23) K atoms
1g of Potassium would contain 6.022x10^(23) / 39 = 1.544 x10^(22) atoms
So 250g of Potassium would contain 1.544x10^(22) x 250 = 3.86x10^(24) atoms
Answer:
d. white blood cells
Explanation:
It is the white blood cells that have the least tendency to cross the blood- brain barrier.
Blood- brain barrier is psychological barrier and restricts substances that circulate into the blood from crossing over the central nervous system.
Water, glucose as well as sodium ions can easily cross the barrier. As these are good for body supply energy to the brain.
40.1g of nitrogen gas is produced.
The equation given is
2 NH₃ + 3 CuO →3 Cu + N₂ + 3 H₂O
This equation is already balanced.
When 3 moles of CuO are consumed, 1 mole of nitrogen gas is produced.
We get 1 mole of nitrogen from 3 moles of copper oxide.
We need to find the number of moles of nitrogen gas produced when 4.3 moles of copper oxide are consumed.
4.3/3 x 1 = 1.433 mols
- 1.433 mols of nitrogen gas are produced
- The molar mass of nitrogen gas is 14+14 = 28g
- The amount of nitrogen gas produced in grams is 28x1.433 = 40.1g
40.1g of nitrogen gas can be made when 4.3 moles of CuO are consumed.
Learn more about molarity here:
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At STP (standard temperature and pressure conditions), 1 mol of any gas occupies 22.4 L
This rule is applied to O₂
22.4 L volume occupied by 1 mol
Therefore 83.4 L occupied by - 1/ 22.4 x 83.4 = 3.72 mol
stoichiometry of O₂ to H₂O is 1:2
then the number of moles of water produced - 3.72 mol x 2= 7.44 mol
mass of water produced - 7.44 mol x 18.01 g/mol = 134.1 g
correct answer is D
If pH+ is 7
It is Neutral solution
