One of the true/false questions (answers revealed)
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1. Silica gel is placed in the dryer to keep moist materials dry. (Incorrect) 2. Aqueous solutions of sodium chloride, sodium sulfate, and sodium carbonate have a pH of 7. (Incorrect) 3. Error refers to the degree of difference between the measured value and the true value. The smaller the error, the higher the accuracy of the measured value. (Correct) 4. Performing quantitative analysis on a blank sample using the same methods and steps as those for analyzing a sample, without adding any sample, is called a preliminary test. (Error) This post was last edited by Canghai Yili Sha on 2009-3-6 09:12.]
1. Silica gel is placed in the dryer to keep moist materials dry. (√) 2. Aqueous solutions of sodium chloride, sodium sulfate, and sodium carbonate, with a pH of 7. (×) 3. Error refers to the degree of difference between the measured value and the true value. The smaller the error, the higher the accuracy of the measured value. (√) 4. Performing quantitative analysis on a blank sample using the same methods and procedures as those for analyzing the sample, without adding any sample, is referred to as a preliminary test. (×) This post was last edited by limingshuguang on 2009-3-5 11:58.]
1.T2.F3.T4.F ps: The question is very good
1. True 2. False 3. True 4. False
1. Silica gel is placed in the dryer to keep moist materials dry. ( X ) 2. Aqueous solutions of sodium chloride, sodium sulfate, and sodium carbonate, with a pH of 7. ( X ) 3. Error refers to the degree of difference between the measured value and the true value. The smaller the error, the higher the accuracy of the measured value. ( X ) 4. Conducting a quantitative analysis of a blank sample using the same methods and steps as those for analyzing the sample, without adding any sample, is referred to as a preliminary test. ( X )
Question 1: Incomplete. Substances that are prone to deliquescence are added in order to prevent deliquescence. Question 2: Incorrect; the pH of sodium carbonate is around 11. Question 3: Correct. Question 4: It should be called a control experiment; it’s not clear whether a preliminary experiment is also considered a control experiment
1.√ 2.X 3.√ 4.X
1. Wrong; keep dry items to prevent moisture absorption. 2. Wrong; an aqueous solution of sodium carbonate is alkaline. 3. Correct. 4. Wrong; it is the reagent used in the blank experiment
1. Wrong, 2. Wrong, 3. Right, 4. Wrong,
1 wrong 2 wrong 3 wrong 4 wrong
1. Silica gel is placed in the dryer to keep moist materials dry. (Incorrect) 2. Aqueous solutions of sodium chloride, sodium sulfate, and sodium carbonate have a pH of 7. (Incorrect) 3. Error refers to the degree of difference between the measured value and the true value. The smaller the error, the higher the accuracy of the measured value. (Yes) 4. Performing quantitative analysis on a blank sample using the same methods and steps as those for analyzing the sample, without adding any sample, is called a preliminary test. ( Wrong )
1. True 2. False 3. True 4. False
1. Silica gel is placed in the dryer to keep moist materials dry. (Yes) 2. Aqueous solutions of sodium chloride, sodium sulfate, and sodium carbonate have a pH of 7. (Incorrect) 3. Error refers to the degree of difference between the measured value and the true value. The smaller the error, the higher the accuracy of the measured value. (Yes) 4. Performing quantitative analysis on a blank sample using the same methods and steps as those for analyzing the sample, without adding any sample, is called a preliminary test. ( Wrong )
1. Silica gel is placed in the dryer to keep moist materials dry. (Incorrect) 2. Aqueous solutions of sodium chloride, sodium sulfate, and sodium carbonate have a pH of 7. (Incorrect) 3. Error refers to the degree of difference between the measured value and the true value. The smaller the error, the higher the accuracy of the measured value. (Yes) 4. Performing quantitative analysis on a blank sample using the same methods and steps as those for analyzing the sample, without adding any sample, is called a preliminary test. ( Wrong )
1. True 2. False 3. True 4. False
1、Wrong 2、Wrong 3、Right 4、Wrong
1. Silica gel is placed in the dryer to keep moist materials dry. (Yes) 2. Aqueous solutions of sodium chloride, sodium sulfate, and sodium carbonate have a pH of 7. (Incorrect) 3. Error refers to the degree of difference between the measured value and the true value. The smaller the error, the higher the accuracy of the measured value. (Yes) 4. Performing quantitative analysis on a blank sample using the same methods and steps as those for analyzing the sample, without adding any sample, is called a preliminary test. ( Wrong )
1、× 2、× 3、× 4、×:)
1. True 2. False 3. True 4. False
For the first question, it’s incorrect; desiccants are added to keep the contents dry and protected from moisture. Question 2: Incorrect. Because the pH of sodium sulfate is not 7, but greater than 7. For question three, yes. Accuracy indicates the degree of closeness between the measured value and the true value; therefore, it should be measured using error. The smaller the error, the higher the accuracy of the analysis results. For question four, it’s correct.
1. True 2. False 3. True 4. False