Answer:
there is no d electron that can be promoted via the absorption of visible light 
Explanation:
One of the properties of transition elements is the possession of incompletely filled d orbitals. This property accounts for their unique colours.
The colours of transition metal compounds stem from d-d transition of electrons due to the presence of vacant d orbitals of appropriate energy to which electrons could be promoted.
For elements whose atoms have a d10 configuration, such vacant orbitals does not exist hence their compounds are not colored.
Sometimes, the colour of transition metal compounds stem from ligand to metal charge transfer(LMCT) for instance in KMnO4.
 
        
             
        
        
        
13
Al
Aluminum
Atomic mass 26.982
        
                    
             
        
        
        
Answer: Small groups of atoms that are attached to larger molecules, giving the specific chemical properties, are called functional groups.
explanation: Functional groups are groups of atoms in a molecule that possess the same chemical feature every time it appears in several compounds. There are various types of functional groups and they have the tendency to react in definite ways. Examples include; the ether functional group (consists of an oxygen atom that forms single bonds with two carbon atoms),the alcohol functional group (consists of an oxygen atom that is bonded to one hydrogen atom and one carbon atom), and the amine functional group (consists of a nitrogen atom bonded to some combination of carbons and hydrogens).
        
             
        
        
        
We have to complete all the given reactions.
1. Fe(s) + CuCl₂ → Cu + FeCl₂
2. Cu(s) + FeCl₂(aq)  → NR (no reaction takes place)
3. K(s) + NiBr2(aq) → NR (no reaction takes place)
4. Ni(s) + KBr(aq) → K + NiBr₂
5. Zn(s) + Ca(NO₃)₂(aq) → NR (no reaction)
6. Ca(s) + Zn(NO₃)₂(aq) → Zn(s) + Ca(NO₃)₂(aq)