What holds the molecules together in a sample of ammonia, nh3? a. dipole-dipole attraction b. polar covalent bond c. hydrogen bonding d. london dispersion?

b. Polar covalent bonds. The polar N-H bonds hold the NH3 molecules together. They are intramolecular forces of attraction within a molecule.

All the other options are wrong. They are intermolecular forces — the attractive forces between different molecules.

a saline water is fed to a reverse osmosis unit at flow rate o rotameter connected to reject (retentate) line reads 8 installed in reject and permeate line reads 15.2 milli siemens/cm and 300 micro siemens/com respectively.