Question

Which of the following has two significant figures?A.) 10 gB.) 0.01 gC.) 120 gD.) 0.120 g

Answer 1

Answer: A. 10 g

Step-by-step explanation:

Significant figures are those digits which carry any meaning when they are resolved. Digits exclusively are from 0 to 9. Rules that are followed to select significant figures are:

1. All the non-zero digits are considered to be significant

2. If there are zeroes between non-zero digits, they are considered to be significant.

3. A zero at the right end of the decimal is considered to be significant.

In the above question;

A has 2 significant figures, whereas B has 1 significant figure, C has 3 significant figures and D also has 3 significant figures.

Answer 2

Step 1 - Understanding what two significant figures means

A significant figure is a digit that is "reliable or absolutely necessary to define the number or measurement". The following are not counted as significant figures:

1) Leading Zeros: numbers such as 0.057 or 0.068 have only two significant figures. The zeros at the beggining do not count.

2) Trailling Zeros: are not counted as significant in measurements.

Spurious digits are also not counted as significant figures.

In this case, number with two significant figures are like 22, 0.0045, 130, 7500 and so on.

Step 2 - Analysing the problem to discover the significant figures

Let's analyse the given numbers:

`\begin{gathered} 10\to\text{ trailling zero does not count; sig fig: 1} \\ \\ 0.01\to\text{ leading zeros does not count; sig fig: 1} \\ \\ 120\to\text{trailling zero does not count; sig fig: }2 \\ \\ 0.120\to\text{ leading zero does not count; sig fig: 3} \end{gathered}`

The measurement with two significant figures is therefore c) 120 g.