Question

discovered in modern times.
use the data in the table to complete the line graph below.
number of known chemical elements

year	known elements
1855	40
1905	60
1955	80

click to select points on the graph.
number of known chemical elements
\

$$\begin{tikzpicture} \\begin{axis} title={number of known chemical elements}, xlabel={year}, ylabel={known elements}, xmin=1800, xmax=2000, ymin=0, ymax=90, xtick={1805,1855,1905,1955}, ytick={0,10,20,30,40,50,60,70,80,90}, legend pos=north west, ymajorgrids=true, grid style=dashed, \\addplotmark=*, color=blue coordinates {(1805,20) (1855,40) (1905,60) (1955,80)}; \\end{axis} \\end{tikzpicture}$$

Explanation:

Step1: Plot 1805 data point

Locate x=1805, y=20 on graph, mark the point.

Step2: Plot 1855 data point

Locate x=1855, y=40 on graph, mark the point.

Step3: Plot 1905 data point

Locate x=1905, y=60 on graph, mark the point.

Step4: Plot 1955 data point

Locate x=1955, y=80 on graph, mark the point.

Step5: Connect plotted points

Draw straight lines between consecutive points.

Answer:

The completed line graph has the following points plotted and connected:

• (1805, 20)
• (1855, 40)
• (1905, 60)
• (1955, 80)