Answer:
Water sample showing pink/purple color is an error.
Explanation:
Biuret is a blue color reagent that changes its color to pink/purple whenever it detects protein in a sample. Water don't contain proteins so it should not show pink/purple color instead it should maintain the blue color. Food items generally contain proteins so it show pink/purple color but it showed blue color.
Error might have caused by wrong marking of the samples, test tube marked with Water might contain a mystery food while Mystery food tube might contain water.
 
        
                    
             
        
        
        
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It can be called<span> a draw, a wash or a gulch</span>
        
                    
             
        
        
        
Sound waves enter the outer ear and pass into the ear canal where the waves cause the eardrum to vibrate.
Hope this helps you.<3