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Question 26
Calculate the molar mass of Ca(NO3)2.
Answer:
Molar mass = 40.08 + (2 x 14.01 + 6 x 16) = 164.1 g mol-1
Question 28
The most common form of scandium has a mass number of 45 and has 24 neutrons. Calculate how many electrons it has.
Answer:
Since the mass number is the number of neutrons plus the number of protons, then scandium has 45 - 24 = 21 protons.
Hence it has 21 electrons since the number of protons equals the number of electrons.
