Is France particularly vulnerable to terror attacks and is there a reason for this?

France is no more vulnerable than other countries to terror attacks. Yes, it has experienced some truly horrible incidents such as the Bataclan incident. But such episodes are dotted around Europe and have affected Britain, Spain, and Germany for instance. One reason for the vulnerability that all countries share is that it's often difficult to attribute a specific incident to ISIS with certainty. What seems to be the case much of the time is that an individual who is sympathetic to their aims and is at a bad point in their life decides to act against a society they feel - perhaps with justification - has treated them badly, and respond to that decision with a violent act. When that act is carried out by someone who is not white, it's more likely to be declared terrorism - compare for example with the number of white on black attacks in America where the killer is never declared to be a terrorist despite holding extreme right views and being a member of an organisation dedicated to undemocratic aims. The other thing that happens in the aftermath of so-called terrorist incidents is that ISIS claims that they were responsible, though it's frequently impossible to generate a link between ISIS and the perpetrator of the attack. And France is no more vulnerable to such episodes than ohter countries.