Explanation:
The most reactive metals are found on the left of the periodic table, in the blue column, known as the alkali metals. Their reactivity increases as we go down column (group) one. Reactive metals, when attached to less reactive metals, have the ability to prevent the less reactive metal from rusting.
Answer:

Explanation:
Half time is period required to desintegrating the half of the initial number of atoms. Then, the total time is:


Sound travels in waves and the height of the wave is the loudness of the sound.
To decrease sound, you need to make the waves not so high, so you can
- decrease the amplitude
- decrease the height of the crest (lower the top of the wave down)
- increase the height of the trough (bring the bottom of the wave up)
It's all about getting the wave to be closer to the center, to not be so high and low, but to be flatter.
(picture taken from sound . eduation website)
Isotopes of any given factor all incorporate the equal variety of protons, so they have the identical atomic wide variety (for example, the atomic wide variety of helium is usually 2). Isotopes of a given factor include exceptional numbers of neutrons, therefore, special isotopes have special mass numbers.