Answer:
the answer is the 2nd option . it has 3 structural isomers
A) iron melting is the only example of physical change, because it's just a change of state (from solid to liquid).
The others, rusting, combustion, and decay are all chemical changes, because it will result in changing the chemical bonds between the atoms.
Answer:
As any molecular or ionic compound, 0 net charge, as a hypothetical diatomic cation, 2+
Explanation:
The question states that this is a compound, and any molecular or ionic compound would have a net charge of 0.
However, such a compound doesn't exist. Francium generally exists in nature having a 1+ charge in its cation form. Combining two francium ions would result in a 
species which is simply a diatomic ion but not a compound.
It oxidized cu since it gains electons.
Answer:
4.504g of acetic acid
Explanation:
The acetic acid in reaction with NaOH produce acetate ion, thus:
CH₃COOH + NaOH → CH₃COO⁻ + H₂O + Na⁺
<em>That means the moles of acetate buffer comes, in the first, from the acetic acid</em>
As you need 500mL (0,500L) of a 0.150M acetate buffer, moles are:
0.500L × (0.150mol / 1L) = <em>0.075 moles of acetate</em>. That is:
0.075mol = [CH₃COO⁻] + [CH₃COOH]
Thus, grams of acetic acid you need to prepare the buffer are:
0.075 moles acetic acid × (60.05g / 1mol) = <em>4.504g of acetic acid</em>
