Answer:
a) element
b) compound
c) element
d) compound
Explanation:
a) Hydrogen is the chemical element with the symbol H; is the lightest element in the periodic table.
b) Water: It is a substance whose molecule is composed of two atoms of hydrogen and one of oxygen.
⇒ molecular formula: H2O
c) gold: is the chemical element with the symbol Au. It is a very dense, soft and intense yellow metal.
d) sugar: it is a compound whose chemical formula is C12H22O11
Answer:tetrahedral
Explanation:
According to Valence Shell Electron Pair Repulsion Theory (VSEPR). The number of electron pairs on the valence shell of the central atom in a molecule influences the shape of that molecule. Four electron pairs around the central atom of a molecule leads to a tetrahedral geometry as predicted by VSEPR.
Answer:
aluminum is highly reactive
Final amount =initial anount *(1/2)^(t/half life)
final amount =2.000 mg *(1/2)^(10.5/5.20) = 0.493 mg remain after 10.5 years