5. What is common among the following phenomena? * Blinking of traffic light
* Rotation of blades of fan
* Swinging of pendulum of a clock

a) All are chemical changes
b) All are periodic changes
c) All are undesirable changes
d) All are irreversible changes

Which statement describes both homogeneous mixtures and heterogeneous mixtures?

Astudent is trying to create a table that compares hypotheses, theories, and laws. hypothesis theory law do scientific researchers formulate it? yes yes yes does it explain why things happen? yes yes no yes yes yes is it used to make predictions? no yes yes which of the following questions would most likely fill the blank in the table? is it an intelligent guess? is it newly formulated? is it based on observations? has it been proved?

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ?