13. __ Standards are prepared in the laboratory for a specific analysis: a) Primary b)Secondary c) Precipitation d)Titration

The correct answer is a) Primary.<br /><br />Primary standards are substances that are used to prepare standard solutions for calibration in analytical chemistry. They are characterized by their high purity, stability, non-hygroscopic nature, and non-toxicity. Primary standards are typically prepared in the laboratory for a specific analysis to ensure accuracy and reliability in the results.