Moles of hydrochloric acid (HCl) present in 72.9g is 2 moles.
Moles of any substance will be calculated as:
n = W/M, where
W = given mass
M = molar mass
Moles of 72.9g of hydrochloric acid whose molar mass is 36.45 g/mole will be calculated as:
n = 72.9 / 36.45
n = 2 moles
Hence required moles is 2 moles.
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