As with the Roman alphabet, which you may be familiar with it (since you are using it to read this answer), different letters have different symmetries.
In caps there is 1. lower case none.
Not many. Depending on how you write, the letters L, O, Q, and X can have diagonal lines of symmetry.
zero, all the keys have different letters, numbers, or symbols
the answer is U O S H K Z X N A D=2 0R MORE LINES OF SYMMETRY
2 lines OF SYMMETRY
Pi has 2 lines of symmetry
None.
O and X And H and I (Note "O" has many, actually an infinite number of, lines of symmetry)
Five.H , I , O , X( ' O ' has 2 lines of symmetry and more besides and ' X ' has 4 )
Seven
None. Some letters have one or more but all the letters, taken as a set, have none.
In caps there is 1. lower case none.
Not many. Depending on how you write, the letters L, O, Q, and X can have diagonal lines of symmetry.
zero, all the keys have different letters, numbers, or symbols
the answer is U O S H K Z X N A D=2 0R MORE LINES OF SYMMETRY
A nephroid has 2 lines of symmetry.
it has five lines of symmetry