Many scientist use dichotomous key
Answer:
change in enthalpy for 1 lb water is - 970.10872 Btu
Explanation:
Given data:
weight of water 1 lb
pressure 1 atm
temperature 212 Fahrenheit
From steam table
initial enthalpy 
final enthalpy
change in enthalpy is given as



change in enthalpy for 1 lb water is - 970.10872 Btu
Answer:
Moles of water in 7.1×10²⁵ molecules are 118 mol.
Explanation:
Given data:
Number of molecules of water = 7.1×10²⁵ molecules
Moles of water in 7.1×10²⁵ molecules = ?
Solution;
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
For example,
1 mole = 6.022 × 10²³ molecules of water
7.1×10²⁵ molecules of water × 1 mol / 6.022 × 10²³ molecules of water
1.18×10² moles of water 0r 118 moles of water