Question

The uncertainty in the experimental or the calculated values is indicated by mentioning the number of significant figures. Significant figures are meaningful digits which are known with certainty plus one which is estimated or uncertain. The uncertainty is indicated by writing the certain digits and the last uncertain digit. Thus, if we write a result as 11.2 mL, we say the 11 is certain and 2 is uncertain and the uncertainty would be +1 in the last digit. Unless otherwise stated, an uncertainty of +1 in the last digit is always understood. There are certain rules for determining the number of significant figures. (1) All non-zero digits are significant. (2) Zeros preceding to first non-zero digit are not significant. (3) Zeros between two non-zero digits are significant. (4) Zeros at the end or right of a number are significant, provided they are on the right side of the decimal point. (5) Counting the numbers of object have infinite significant figures.

Precision refers to the closeness of various measurements for the same quantity. However, accuracy is the agreement of a particular value to the true value of the result. For example, if the true value for a result is 2.00 g and student 'A' takes two measurements and reports the results as 1.95 g and 1.93 g. Another student 'B' repeats the experiment and obtains 1.94 g and 2.05 g as the results for two measurements. When the third student 'C' repeats these measurements and reports 2.01 g and 1.99 g as the result.