Answer:
NH₄Cl, Magnesium sulfate, KCN
Explanation:
Determine whether the given compound name or formula contains a polyatomic ion.
- NH₄Cl. YES. It contains the polyatomic ion ammonium NH₄⁺.
 
- Magnesium sulfate. YES.  It contains the polyatomic ion sulfate SO₄²⁻.
 
- Sodium phosphide Na₃P. NO.
 
- Calcium hydroxide Ca(OH)₂. NO.
 
- KCN. YES. It contains the polyatomic ion cyanide CN⁻.
 
 
        
             
        
        
        
Answer: 116g/mole
Explanation:
She didn't get the answer because she didn't add the them well , due to the bracket present. 
 
        
             
        
        
        
Answer:
It's b
Explanation:
I had the same exact question
 
        
             
        
        
        
Answer:
23.34 %.
Explanation:
- The percentage of water must be calculated as a mass percent.
 
- We need to find the mass of water, and the total mass in one mole of the compound. For that we need to use the atomic masses of each element and take in consideration the number of atoms of each element in the formula unit.
 
- <em>Atomic masses of the elements:</em>
 
Cd: 112.411 g/mol, N: 14.0067 g/mol, O: 15.999 g/mol, and H: 1.008 g/mol.
- <em>Mass of the formula unit:</em>
 
Cd(NO₃)₂•4H₂O
mass of the formula unit = (At. mass of Cd) + 2(At. mass of N) + 10(At. mass of O) + 8(At. mass of H) = (112.411 g/mol) + 2(14.0067 g/mol) + 10(15.999 g/mol) + 8(1.008 g/mol) = 308.5 g/mol.
- <em> Mass of water in the formula unit:</em>
 
<em>mass of water</em> = (4 × 2 × 1.008 g/mol) + (4 × 15.999 g/mol) = 72.0 g/mol.
- <em>So, the percent of water in the compound = [mass of water / mass of the formula unit] × 100 = [(72.0 g/mol)/(308.5 g/mol)] × 100 = 23.34 %</em>