Answer:
a
Explanation:
Because of their valence electron
Carbon, Silicon and germanium has 4 as their valence electron
Answer:
The filter bed is cleaned by occasional backwashing ;-; im sorry if this isn't a great answer but I tried
Answer:

Explanation:
Hello,
In this case, the only source of hydrogen is in the 6 molecules of water, therefore, the atoms of hydrogen, by applying stoichiometry with the Avogadro's number is:

Best regards.
Answer:
An element
It stays shiny
Explanation:
Pure Gold is an element.
An element is a distinct substance that cannot be split-up into simpler substances. Such substances consists of only one kind of atom.
There are over a hundred elements known to date.
As an element, Gold is classified as a metal due to its very unique set of properties.
One of the indicator that gold does not react with oxygen is that it stays shiny. It does not give rusty look when exposed to air.
Substances that combines with oxygen have a rusty look or change appearance when expose to air. For example, iron.
A rock is a solid, so Logan can't poke his finger through it.