Code:
public static string ValidateName ( string name )
 {
 string trimmedName = name.Trim();
 if ( trimmedName.Length == 0 )
 {
 return "No text in the name";
 }
 return "";
 }
1. The code above removes extra white space (This removes the possibility of having a length greater than 0 without actual characters). Then checks to see if the length is equal to 0. If so, sends a reply to a boolean method to be processed. If greater than 0 sends an empty reply.

Code:
public Account ( string inName, decimal inBalance )
 {
 if ( !SetName(inName) )
 {
   throw new Exception("Invalid name");
 }
if(inBalance < 0 || > 10000)
throw new Exception("Invalid Balance");
else
 this.balance = inBalance;
 }

2. A call to a static method generates a call instruction in Microsoft intermediate language (MSIL). whereas a call to an instance method generates a callvirt instruction, which also checks for a null object references. However, most of the time the performance difference between the two is not significant. So it's slightly faster than non-static because it does less.

3.
Code:
public Account ( string inName)
 {
 if ( !SetName(inName) )
 {
 throw new Exception("Invalid name");
 }
 this.balance = 0;
 }
4. the ToString method returns whatever value as a string.
Code:
    protected string ToString(object obj)
    {
        return obj.ToString();
    }
5.
Code:
public void TestBank()
{
 
Account acc = new Account("Kiryn");
Account acc1 = new Account("", 1337);
Account acc2 = new Account("Kiryn", -50);
Account acc3 = new Account("Kiryn");
acc3.payInFunds(50);
acc3.getBalance();
}

6.
Code:
private decimal limit;
Code:
public override bool WithdrawFunds ( decimal amount )
 {
 if (amount > limit)
 {
 return false ;
 }
 return base.WithdrawFunds(amount);
 }
Code:
    public decimal Limit { 
        get {
            return limit;
        } 
        set {
            limit = value;
        } 
    }
}
Edit: this took me like 20min bro. In the time you spent posting on the forums you could've had it done.