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.
I'm not sure what issues you are having, but my copies of Excel 2007 and 2010 both allow you to insert another Excel sheet as an object. 1  To do it, you need to click on the Insert tab in the ribbon, and then click Object. This will open a dialog window allowing you to set the object to insert. Click on the Create from file tab to insert your specific file. Click Browse button and select the file you are looking to insert.