6. Drop to one quarter of its original value
Answer: Rubidium has 5 orbits/shells/energy levels.
Explanation: It's electron configuration is as follows: 2-8-18-8-1.
You should trust the primary source more.
This is because the primary source is make its conclusion from direct observation, while the secondary source is possibly making reference to another secondary source or to another primary.
The primary source should be trusted more because it is from direct observation.
It does produce 'sound' ... a compression wave traveling through the air. But your ears don't hear a sound that's vibrating less than 20 or 30 times every second. If you could swing your pendulum that fast, you could hear the sound of its vibrations pushing the air around.
Water is a very unique substance because it can exist in all three phases of matter (solid, liquid, gas) within the normal temperature ranges found on Earth. When one observes the phase of matter of water, one observes a property of matter.
