Nitrate test to 2.5 micrograms and a concentration of 1 in 25,000 parts. Devarda's alloy (Copper/Aluminium/Zinc) is a reducing agent. When reacted with nitrate in sodium hydroxide solution, ammonia is liberated. The ammonia formed may be detected by its characteristic odor, and by damp red litmus paper's turning blue, signalling that it is an alkali — very few gases other than ammonia evolved from wet chemistry are alkaline. Aluminium is the reducing agent in this reaction that will occur. Diphenylamine may be used as a wet chemical test for the presence of the nitrate ion. In this test, a solution of diphenylamine
Teaching to the test a test over the information at the end of the unit. Typically, these tests aim to make sure that students have memorized a series of procedures, rather than making sure that the students fully understand what they are doing; in other words, these tests are a measure of a student's arbitrary knowledge rather than his or her capacity for logical thinking. Teaching to the test is also frequently used for skill-based learning, like typing or athletics; in this context, teaching to the test is the dominant practice. For one reason, teaching to the test misrepresents how much students really have