Answer:
The air resistance is a special type of frictional force that acts upon objects as they travel through the air. The force of air resistance is often observed to oppose the motion of an object. This force will frequently be neglected due to its negligible magnitude (and due to the fact that it is mathematically difficult to predict its value). It is most noticeable for objects that travel at high speeds (e.g., a skydiver or a downhill skier) or for objects with large surface areas. Air resistance is a contact force.
The force of gravity is the force with which the earth, moon, or other massively large object attracts another object towards itself. By definition, this is the weight of the object. All objects upon earth experience a force of gravity that is directed "downward" towards the center of the earth. Gravitational force is considered to be a non-contact force because it is an attracting force which does not include contact between the objects to exert force
Elements in the same group tend to have very similar properties (D). This is due to the number of valence electrons each group has.
You can promote collisions between molecules when you increase their kinetic energy by either increasing the temperature or pressure conditions of the systems. However, it is indicated that you must not change the energy. So, we eliminate choices C and D. Choice B is contradictory to the limitation that you do not increase the concentration of the reactants. Technically, all of the choices promote frequent collisions. But due to the limitations set, the accepted answer is letter A. When you increase the surface area by using powdered reactants instead of cubes, you increase the areas for susceptibility of collisions.
A climograph is a dual-purpose graph, showing two different kinds of information. A bar graph shows how much precipitation a given place receives during a period of time. A line graph shows the temperature conditions for the same place during the same period of time.