The given salinity is 24ppt
The relation between salinity and grams is

it means there is 24 parts of salt per 1000 parts of water
ppt: parts per thousand
Or
there is 24 grams of salt per 1000g of water
thus the value 24 ppt signifies that there is 24g of salt dissolved in 1000g or 1kg of water
B. Carbon changes from one form to another, but the total amount of carbon remains the same.
Molecular geometry about the left carbon atom in CH₃CO₂CH₃ is tetrahedral.
The geometry around left carbon that is CH₃ is tetrahedral.
As the hybridization around left carbon is sp³ that shows its geometry should be tetrahedral and as there are 4 ligands around carbon and there is no lone pair present so the geometry is tetrahedral. So, the molecular geometry about the left carbon atom in CH₃CO₂CH₃ is tetrahedral.