1 Cropping an image means to select a rectangular region to use. 2  To crop an image: 3  Right click on the image file in the File Explorer, select Open With, Paint. 4  Right click on the Select item in the toolbar.  Depress the left mouse button at the upper left corner of the rectangular region you wish to select.
TNT is made by adding 3 NO 2 groups (from nitric acid) to toluene. At low temperatures, the mononitrotoluenes are made, and as the reaction temperature is increased the dinitro compounds are formed, until eventually TNT is formed. TNT is explosive for two reasons. First, it contains the elements carbon, oxygen and nitrogen, which means that when the material burns it produces highly stable substances (CO, CO 2 and N 2) with strong bonds, so releasing a great deal of energy.
How Concrete is Made. In its simplest form, concrete is a mixture of paste and aggregates, or rocks. The paste, composed of portland cement and water, coats the surface of the fine (small) and coarse (larger) aggregates.Through a chemical reaction called hydration, the paste hardens and gains strength to form the rock-like mass known as concrete.he paste, composed of portland cement and water, coats the surface of the fine (small) and coarse (larger) aggregates. Through a chemical reaction called hydration, the paste hardens and gains strength to form the rock-like mass known as concrete.