At 25C, 0.212g of barium hydroxide is dissoleved completely to make 0.25 litre of final solution. What is the hydroxide ion concentration (in mol litre-1) in this solution, answer in scientific notation to an appropriate number significant fiqures, and state the assumption you must make in order to carry out the calculation.
Please can you help I have got in a muddle and now I am not sure if what I have done is right Thank you