3.42 g of sucrose are dissolved in 18g of water in a beaker. The number of oxygen atoms in the solution are

Molar mass of sucrose (C₁₂ H₂₂ O₁₁) = 342g/mole

Thus,

Number of moles of sucrose = Given mass/ Molar Mass

=

1 mol of sucrose contains = 1× N_A sucrose molecules = 11 x N_A atoms of oxygen

0.01 mol of sucrose (C₁₂ H₂₂ O₁₁) contains = 0.01 × 11 × N_A atoms of oxygen

= 0.11× N_A atoms of oxygen

Molar mass of water = 18g/mole

Thus, Number of moles of water =

1 mol of water (H₂O) contains = 1×N_A water molecules = 1 x N_A atoms of oxygen

Total number of oxygen atoms = Number of oxygen atoms from sucrose + Number of oxygen atoms from water

= 0.11 N_A + 1.0 N_A = 1.11N_A

Number of oxygen atoms in solution = 1.11 × Avogadro’s number

= 1.11 × 6.022 ×10²³

= 6.68 × 10²³