Answer:
C. 6.99 moles
Step-by-step explanation:
To convert molecules to moles we simply divide the given number of molecules by Avogadro's number, 6.022 x 10²³
Given number of molecules : 4.21 x 10^24
Number of moles : 4.21 x 10^24 / 6.022 x 10²³ = 6.99 moles ( rounded )
The answer is C