Answer:
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Air & noise pollution
Quarry waste
Damage to biodiversity
Answer:
Four electrons are present in the valence shell of Silicon.
Explanation:
Valence shell electrons are those electrons which are present in the outermost shell of an atom. These valence shell electrons are responsible for in the formation of bonds with other atoms.
Silicon having atomic number 14 has fourteen electrons in its neutral state and has the electronic configuration as follow;
1s², 2s², 2p⁶, 3s², 3p²
In given configuration the valence shell (outermost shell) is 3 and the number of electrons present in it are four i.e. 3s² and 3p² (2 + 2 = 4) respectively.
Answer:
2. All the naturally occurring isotopes of Mg.
Explanation:
You want to know the atomic mass of the magnesium you use in the lab. That’s “natural” magnesium. So, you must use the weighted average of all the naturally occurring isotopes in natural Mg.
1. and 3. are <em>wrong</em>. You won’t get the correct mass for natural Mg if you use only the artificial isotopes for your calculation.
4. is <em>wrong</em>. You must use all the naturally occurring isotopes. The two most abundant isotopes of Mg account for only 90 % of the atoms. If you ignore the other 10 %, your calculation will be wrong.
