What is the concentration of a solution containing 2g of NaOH in 100cm3 of solution? [Na = 23, O = 16, H = 1]

To calculate the concentration of a solution, we need to know the number of moles of the solute (in this case, NaOH) dissolved in a given volume of solution. To do this, we first need to calculate the number of moles of NaOH present in 2g of the compound. The molar mass of NaOH can be calculated as follows: NaOH = 23 + 16 + 1 = 40 g/mol This means that one mole of NaOH weighs 40g. To calculate the number of moles of NaOH in 2g, we can use the following formula: number of moles = mass ÷ molar mass So, the number of moles of NaOH in 2g can be calculated as follows: number of moles = 2 ÷ 40 = 0.05 moles Now that we know the number of moles of NaOH in the solution, we can calculate its concentration. Concentration is usually measured in units of mol/dm3 (moles per cubic decimeter). In this case, we have 100cm3 of solution, which is equivalent to 0.1dm3. So, we can use the following formula to calculate the concentration: concentration = number of moles ÷ volume of solution Substituting the values we have, we get: concentration = 0.05 moles ÷ 0.1 dm3 concentration = 0.50 mol dm-3 Therefore, the concentration of the solution containing 2g of NaOH in 100cm3 of solution is 0.50 mol dm-3. In summary, the concentration of the solution can be calculated by first determining the number of moles of the solute in the solution, and then dividing it by the volume of the solution. For the given solution, the number of moles of NaOH in 2g is 0.05 moles, and the concentration is 0.50 mol dm-3 when dissolved in 100cm3 of solution. Therefore, the correct option is B: 0.50 mol dm-3.