How many moles are present in 1.25x1023 molecules of salt (NaCl)?

0.21 mole of NaCl

Explanation:

From the question,

using Avogadro's Constant,

1 mole of every compound contains 6.02×10²³ molecules of that compound.

I.e

1 mole of NaCl ⇒ 6.02×10²³ molecules of NaCl

x moles of NaCl ⇒ 1.25××10²³ molecules of NaCl

Solving for x,

x moles of NaCl = (1 mole of NaCl)×(1.25×10²³ molecules of NaCl)/(6.02×10²³ molecules of NaCl)

x moles of NaCl = (1×1.25×10²³)/6.02×10²³

x = 0.208 mole of NaCl

x ≈ 0.21 mole of NaCl

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the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3