From the diagram, when the temperatures of reactants are raised from 20°C to 30°C:
The average kinetic energy doubles.
The pumber of molecules doubles.
The total number of collisions doubles.
The number of molecules having E, or greater doubles.

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.