For the rate of collisions to increase, It can happen in various ways
1. The gasses can be made to move faster: This can be done by increasing their temperature. An increase in the temperature of the gases directly relates to a corresponding increase in their kinetic energy. This means that the molecules of the gases can move with a greater velocity, which will increase collision rates.
2. The volume of the container can be reduced: Consider this; If the container is made smaller, the molecules of the gases will have less space to move about. This means that they will be bumping into the walls of the container more frequently. This reduction in volume leads to an increase in the pressure of the gas. This is exactly what happens in a piston-cylinder assembly
A scientist can assess whether a pure niobium sample is responsible for contaminating the lab with radioactivity by testing the sample. By testing the niobium sample, a scientist can determine whether it has any other element.