Answer:
5.7 pH
Explanation:
To find pH when given [H+], you use this formula: pH = -log[H+]
-log * 2.1e-6 = 5.6778 = 5.7 pH
Answer: I believe it's convection
Good luck and I hope this helps!!
Answer:

one atom of an element = 6.02 \times {10}^{23} atom
The mass of one atom of sulphur = 32g
The mass of one atom of aluminium = 27g
so one atom of aluminium = 6.02 \times {10}^{23}
27g of AL = 6.02 \times {10}^{23} atom
2.70g of AL = X atoms
Then you cross multiply ........
and get the answer
.