Step-by-Step Solution:

1. Understand the Hydrolysis of a Decapeptide A decapeptide is a polymer made of 10 amino acid units joined by 9 peptide bonds. During complete hydrolysis, these 9 peptide bonds are broken, and a molecule of water is added to each bond. The overall reaction can be represented as: $\text{Decapeptide} + 9 \text{H}_2\text{O} \rightarrow 10 \text{ Amino Acids (hydrolysed products)}$

2. Calculate the Total Mass of the Hydrolysed Products The total mass of the hydrolysed products (the 10 amino acids) is the sum of the mass of the original decapeptide and the mass of the water molecules consumed during hydrolysis. This is due to the law of conservation of mass.

   • Molecular weight of the decapeptide = 796 g/mol
   • Molecular weight of water (H₂O) = 18 g/mol
   • Number of water molecules added = 9

   Mass of water added = $9 \times 18 = 162$ g/mol

   Total mass of hydrolysed products = Mass of decapeptide + Mass of water added $\text{Total mass} = 796 + 162 = 958 \text{ g/mol}$

3. Calculate the Total Mass of Glycine The problem states that glycine contributes 47.0% to the total weight of the hydrolysed products.

   • Percentage of glycine = 47.0%
   • Total mass of hydrolysed products = 958 g/mol

   Mass of glycine = $47.0\% \text{ of } 958$ $\text{Mass of glycine} = \frac{47.0}{100} \times 958 = 0.47 \times 958 = 450.26 \text{ g}$

4. Determine the Number of Glycine Units To find the number of glycine units, we divide the total mass of glycine by the molecular weight of a single glycine molecule.

   • Total mass of glycine = 450.26 g
   • Molecular weight of glycine = 75 g/mol (given)

   Number of glycine units = $\frac{\text{Total mass of glycine}}{\text{Molecular weight of one glycine unit}}$ $\text{Number of glycine units} = \frac{450.26}{75} \approx 6.003$

5. Final Answer Since the number of amino acid units in a peptide must be an integer, we round the calculated value to the nearest whole number. Therefore, the number of glycine units present in the decapeptide is 6.