Answer:
c
Explanation: just a chemachal
Presumptive tests, also known as preliminary tests or field tests, allow drugs to be quickly classified into a particular chemical group, but do not unequivocally identify the presence of a specific chemical compound.
Answer:
3.56x10^24 molecules
Explanation:
The following data were obtained from the question:
Mass of Na2SO4 = 840g
Molar Mass of Na2SO4 = (23 x2) + 32 + (16x4) =46 + 12 + 64 = 142g/mol
From Avogadro's hypothesis, 1mole of any substance contains 6.02x10^23 molecules. This also gives that 1mole of Na2SO4 contains 6.02x10^23 molecules.
If 1 mole (i.e 142g) contains 6.02x10^23 molecules,
Therefore, 840g of Na2SO4 will contain = (840 x 6.02x10^23)/142 = 3.56x10^24 molecules
First, determine the number of moles of gold.
Number of moles = 
Given mass of gold =
Molar mass of gold = 196.97 g/mol
Put the values,
Number of moles of gold = 
= 
or 
Now, molarity = 
Put the values, volume of ocean =
Molarity = 
= 
Thus, average molar concentration =
