When 2.61 g of solid na2co3 is dissolved in sufficient water to make 250. ml of solution, the concentration of na2co3 is: ?

0.0985 M ≅ 0.1 M.

Explanation:

The concentration of the solution can be expressed by Molraity.

Molarity is the no. of moles of solute in 1.0 L of the solution.

M = (mass/molar mass)Na₂CO₃ x (1000/V of the solution)

mass of Na₂CO₃ = 2.61 g,

molar mass of Na₂CO₃ = 105.98 g/mol,

V of the solution = 250.0 mL.

M = (mass/molar mass)Na₂CO₃ x (1000/V of the solution) = (2.61 g / 105.98 g/mol) x (1000 / 250.0 mL) = 0.0985 M ≅ 0.1 M.

the answer your looking for is c).