Hydrogen, oxygen and nitrogen are counted as some most important elements and found abundantly. About 75% of this universe is composed of hydrogen and helps different other matters to sustain. Large starts and planets, electrons and protons are also composed of hydrogen.
A sheet tab appears at the bottom of your worksheet. It has the name of the worksheet on it, which can be changed and you can also change its colour. This can be done by right clicking on it and picking the option from the shortcut menu that appears. By clicking a sheet tab, you can make that sheet the active sheet so that you can work on it.
Tab scrolling buttons. These are the four buttons that appear to the left of the sheet tabs. They are used to bring hidden sheet tabs into view if they are not already visible. This is only of use when there are more sheet tabs than are shown. The number of sheet tabs shown can be changed with the tab split box.