# Some basic concepts of Chemistry - VIII (Important Formulas)

1. There are certain rules for determining the number of significant figures. These are stated below: a) All non-zero digits are significant. For example in 285 cm, there are three significant figures and in 0.25 mL, there are two significant figures.

b)  Zeros preceding to first non-zero digit are not significant. Such zero indicates the position of decimal point. Thus, 0.03 has one significant figure and 0.0052 has two significant figures.

c)  Zeros between two non-zero digits are significant. Thus, 2.005 has four significant figures.

d)  Counting numbers of objects, for example, 2 balls or 20 eggs, have infinite significant figures as these are exact numbers and can be represented by writing infinite number of zeros after placing a decimal
i.e.,2 = 2.000000 or 20 = 20.000000

e)  In numbers written in scientific notation, all digits are significant e.g., 4.01×102        has  three significant figures, and 8.256 × 10–3 has four significant figures.

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