I am sure it is a.12150sn and 11950sn because isotopes are the same atoms but different number of protons
Hi friend
--------------
Your answer
-------------------
Water = H2O
Number of molecules in one mole of water = 6.022 × 10²³ [Avogadro's constant]
Given number of molecules = 2.52 × 10²³
So,
------
Number of moles =

HOPE IT HELPS
The answer is (2). To calculate the density, you need to divide the mass with volume. When doing division, the significant figures of result is the minimal of the numbers using before. So the answer is 2.