Answer:
1.The metalloids; boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), polonium (Po) and astatine (At) are the elements found along the step like line between metals and non-metals of the periodic table.
2.hydrogen
The elements generally classified as nonmetals include one element in group 1 (hydrogen);
3.element iron
The element iron is in group 8, and therefore has two or three apparent valence electrons.
Answer:
Au
Explanation:
For the density of a face-centered cubic:

where
= molar mass of the compound
avogadro's constant
the volume of a unit cell
Given that:
Density
= 19.30 g/cm³
a = 0.408 nm
a = 
a = 
∴



Thus, the molar mass of 197.37 g/mol element is Gold (Au).
Answer:
The molecules in the water become more separated due to heat.
Silicon is the element having a mass of 28.09 g
<u>Explanation</u>:
- Silicon is the element having an atomic mass of 28.09 g / mol. So 28.09 g of silicon contains 6.023
10^23 atoms. One mole of each element can produce one mole of compound.
- The Atomic weight of an element can be determined by the number of protons and neutrons present in one atom of that element. So atomic weight expressed in grams always contain the same number of atoms( 6.023
10^23).
- Avagadro number is the number of atoms of 1 mole of any gas at standard temperature and pressure. It has been determined that 6.023
10^23 atoms of an element are equal to the average atomic mass of that element.