Why halogens other than fluorine show multiple oxidation states ?

Account for the following: Mn shows the highest oxidation state of +7 with oxygen but with fluorine it shows the highest oxidation state of +4.

Why halogens other than fluorine form oxo acids? Describe the order of acidic strength of oxo acids of halogens.

Why fluorine always exhibits oxidation state of -1 ?

Which of the following halogen shows only negative oxidation state ?

Which member of the halogen family (X_2) does not show positive oxidation state (X_2^+) ?