___is the process that exchanges gases between body and the outside air.

Apossible explanation for a set of facts that can be tested by further investigation is called

The period of a pendulum varies directly as the square root of the length of the pendulum and inversely as the square root of the acceleration due to gravity. find the period when the length is 144 cm and the acceleration due to gravity is 980 cm per second squared, if the period is 7pi seconds when the length is 289 cm and the acceleration due to gravity is 980 cm per second squared.

Give one example to show that when substances are mixed, it may result in a chemical or a physical change depending on the conditions.