Does a missed attack expend a charge for Ring of the Ram?

Question

The description for Ring of the Ram states:

While wearing the ring, you can use an action to expend 1 to 3 of its charges to attack one creature you can see within 60 feet of you...On a hit, for each charge you spend, the target takes 2d10 force damage...

Does this mean:

1. No charges are spent if a miss occurs
2. Player must state how many charges an attack will use, and if a miss occurs, those charges are no longer available?
3. A miss uses up a single charge

Answer 1

Yes, a missed attack expends a charge, or charges.

The sequence is as described:

1. expend n charges,
2. determine whether the attack hits
3. if hit: roll 2 n d10 for damage

(This is your #2 interpretation.)

Answer 2

You're spending charges to attack, not to hit

The rule states:

While wearing the ring, you can use an action to expend 1 to 3 of its charges to attack one creature you can see within 60 feet of you

The ring simply allows you to attack, it does not guarantee success.

You declare beforehand that you want to use 1 or 2 or 3 charges, then you make the attack. If you hit, you deal NUM_OF_CHARGES x 2D10 damage. If you miss, you have still expended the charges but you do no damage.