Think of it this way: it is a distribution problem in which you are multiplying the 2 on the outside with each element in the parentheses. Oxygen does not have a number in front of it, so put an imaginary one in front of it to help you. Do the same with Hydrogen since it doesn't have a number in front of it either. Now you know that hydrogen has one ion and oxygen has one... but you must now multiply each of the elements' ions by two. You should now know that Oxygen has 2 ions in Calcium Hydroxide and that there are also 2 ions of Hydrogen in Calcium Hydroxide. Does this make sense?
The low temperature outside lowers the volume of the gas according to Charles' law because this law describes how a gas will behave at constant pressure. It shows that the volume of a given mass of a gas is directly proportional to the absolute temperature provided the pressure remains constant. An increase in temperature leads to an increase in volume while a decrease reduces the volume. This is due to the reduction in the distances traveled by the vibrating particles of the gas because of the lost kinetic energy.
Newton's third law (for every action, there is an equal and opposite reaction) means that in every interaction (in this case, that of the objects in the image), there is a pair of forces acting on the two interacting objects. <span>When you sit on a chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body. There are two forces resulting from this interaction - a force on the chair and a force on your body. This is embodied in the image by the two objects exerting force on each other (indicated by the arrows).</span><span>
Hope this helps.</span>
