Which is an example of a physical change? es )
A)
Mixing blue and yellow paint to create green paint
B)
Adding water and yeast to bread dough in order to make it raise.
C)
Mixing two liquids together in a test tube and the tube becoming warm.
D)
Adding a piece of chalk containing calcium carbonate to a glass of mild
acid causing the formation of a foam of bubbles.

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.