The first one would be it
Answer:
38.7%
41.3%
20%
Explanation:
The percentage composition helps to know the what percent of the total mass of a compound is made up of each of the constituent elements or groups.
To solve this problem:
- find the formula mass by adding the atomic masses of the atoms that makes up the compound.
- place the mass contribution of the element or group to the formula mas and multiply by 100;
Compound:
Ca₃(PO₄)₂
Formula mass = 3(40) + 2[31 + 4(16)]
= 120 + 2(95)
= 120 + 190
= 310
%C =
x 100 = 38.7%
%P =
x 100 = 41.3%
%O =
x 200 = 20%
The answers to this question is b, I did this on Plato
Answer:
1.51 x 10²⁴molecules
Explanation:
Given parameters:
Number of moles of NaCl = 2.5moles
Unknown:
Number of molecules = ?
Solution:
The number of molecules that can be found in a given mole is given as the Avogadro's constant;
1 mole of substance = 6.02 x 10²³ molecules
2.5 mole of NaCl = 2.5 x 6.02 x 10²³ molecules
= 1.51 x 10²⁴molecules