Answer: The mass in 
atoms of zinc is 0.405 g.
Explanation:
Given: Atoms of zinc =
It is known that 1 mole of every substance contains 
atoms. So, the number of moles in given number of atoms is as follows.
As moles is the mass of a substance divided by its molar mass. So, mass of zinc (molar mass = 65.39 g/mol) is calculated as follows.
Thus, we can conclude that the mass in atoms of zinc is 0.405 g.
Answer:The metal complex formed would have the following formula [Cr(NO₂)₆]³⁻. The complex has a net negative charge and hence it can only be isolated as a salt with a positive cation so the formed complex could be isolated as potassium salt. The formula for salt would be K₃[Cr(NO₂)₆].
Explanation:
The metal ion given to us is Cr³⁺ (Chromium) in +3 oxidation state.
The electronic configuration for the metal ion is [Ar]3d³ so there are vacant 3d metal orbitals which are available and hence 6 NO₂⁻ ligands can easily attack the metal center and form a metal complex.
The charge on the overall complex can be calculated using the oxidation states of metal and ligand which is provided.
The (chromium ) Cr³⁺ metal has +3 charge and 6 NO₂⁻ (nitro) ligands have -6 charge and since the ligands will be providing a total of 6 - (negative) charge and hence only 3- (negative ) charge can be neutralized so a net 3- negative charge would be present on the overall complex which is basically present at the metal center :
charge on the complex=+3-6=-3
Let X be the Oxidation state of Cr in complex =[Cr(NO₂)₆]³⁻
X-6=-3
X=-3+6
X=+3
so our calculated oxidation state of Cr is +3 which matches with the provided in question.
As we can see that the overall metal complex has a net negative charge and hence and only positively charged cations can form a salt with this metal complex and hence only potassium K⁺ ions can form salt with the metal complex.
since overall charge present on the metal complex is -3 so 3 K⁺ ion would be needed to neutralize it and hence the formula of the metal salt would be K₃[Cr(NO₂)₆].
I don't understand what is (g).
Maybe the answer is 2H<span>(aq)S</span>₂<span>−2(aq) </span>⇒ <span>H</span>₂<span>S</span>₂.
1 L ------- 1000 cm³
1.45 L ----- ???
1.45 * 1000 = 1450 cm³ ( volume )
Density = 0.710 g/cm³
mass = in Kg
m = D * V
m = 0.710 * 1450
m = 1029.5 g
1 Kg ------- 1000 g
kg -------- 1029.5 g
mass = 1029.5 / 1000
mass = 1.0295 Kg
hope this helps!
