Lung cancer is the top cause of cancer deaths in both men and women. But this wasn't always the case. Prior to the widespread use of mechanical cigarette rollers, lung cancer was rare. Today, smoking causes nearly 9 out of 10 lung cancer deaths, while radon gas, pollution, and other things play a smaller role.
From Wikipedia, the free encyclopedia. A plane symmetry is a symmetry of a pattern in the Euclidean plane: that is, a transformation of the plane that carries any directioned lines to lines and preserves many different distances. If one has a pattern in the plane, the set of plane symmetries that preserve the pattern forms a group. The groups that arise in this way are plane symmetry groups and are of considerable mathematical interest. A symmetry plane is a three-dimensional object's symmetry axe. There are several kinds of plane symmetry groups: Reflection groups.
So 2-chlorobutane does not have a plane of symmetry. It has an asymmetric geometry. Axes of Symmetry. An axis of symmetry corresponds to a rotation by #(360Â°)/n#, where #n# is an integer. A water molecule has one axis and two planes of symmetry. The water molecule is symmetric. To be symmetric, a molecule must have either an axis of symmetry or an imaginary plane that bisects it into mirror-image halves. A molecule that has neither of these is asymmetric.