Answer:
B. 214.02
Explanation:
1 mol of water weighs 18.015 gm and contains 6.023 × 10²³ molecules
From question, We have 7.15 × 10²⁴ molecules
Dividing we get (7.15 × 10 ²⁴) ÷ ( 6.023 × 10²³) = 11.871 molecules
Now, Weight of water = 11.871 × 18.015 = 213.85 which is nearer to option B
Use the atomic mass of potassium, k, 39.1 g/mol, and the formula n = mass / atomic-mass.
Where n is the number of moles.
n = 250.0 g / 39.1 g/mol = 6.3939 mol.
Now multiply by Avogadro number to find the number of atoms:
6.3939 mol * 6.02*1023 atoms/mol = 38.49 * 10^23 atoms = 3.849 * 10^24.
Answer: 3.85*10^24
As you mentioned the question in chemistry so it may be a concentration unit I.e mass per volume.
(SOLUTION)
Mass/volume = total mass/ total volume
Now:
Total mass= 42.95 g
Total volume =351.8mL
Put these values in above equation;
Mass/volume = 42.95/351
“”. = 0.122 g/mL
