Answer : The mass of 5.0 moles of ribose is 750 grams.
Explanation : Given,
Moles of ribose = 5.0 moles
Molar mass of ribose = 150 g/mole
Formula used :

Now put all the given values in this formula, we get:

Therefore, the mass of 5.0 moles of ribose is 750 grams.