Calculate chance level in multiple choice

Hello everyone.

In short: I would like to know how to compute the chance-level of an 8-alternative multiple choice questionnaire with 6 questions.

Here is some more information:

In my experiment, participants viewed 6 stimuli, each stimulus conveying one of the six basic emotions (anger, disgust, fear, happiness, surprise, sadness). Basically, for each stimulus participants were asked which one of the six basic emotions they thought was conveyed in the stimulus. The answer format was a 8-alternative multiple choice, including the label of each basic emotion + neutral emotion + no idea (knowing that neutral emotion and no idea were both regarded as wrong answer for each stimulus).
If they chose the correct emotion of the stimulus, the participants received one point. So at the end, their score could range from 0 to 6.

The mean score of the total sample is 2,3. I would like to know whether this is above chance level.
According to me, the chance level of a 2-alternative multiple choice (like a yes-no questionnaire) would be: 100/2 % * number of questions. So, is it true that in my case, the chance level should be computed as : 100/8 % * 6 = 0,75 ?
So, if the mean score is above 0,75 (which is the case for my sample), can I claim that my sample answered at above-chance level?

Many thanks in advance for your help.