According to Dalton’s law of partial pressures, (where pb = Barometric pressure, pa = Partial pressure of dry air, and pv = Partial pressure of water vapour)

Pb = pa – pv
Pb = pa + pv
Pb = pa x pv
Pb = pa/pv
✅ The correct answer is option B.

Which of the following are the guidelines for the construction of a network diagram?

Each activity is represented by one and only one arrow in the network.
Dangling must be avoided in a network diagram.
Dummy activity consumes no time or resource.
all of the above
✅ The correct answer is option D.