I agree that it’s an imperfect unit of measurement. In fact, the convention is often ignored due to its proneness to causing confusion. Regardless, a convention is a convention and currently the answer to question 5 is incorrect according to the modern conventions of Chemistry and Calorimetry. Wikipedia’s article on the Calorie has an excellent section under History detailing the difficulties arising from distinguishing between the so-called “large” calorie and “small” calorie, I encourage you to read into it. Unfortunately, it’s such a subtle inaccuracy that I doubt QM will fix it, however, as an Astrophysics major with a love for Chemistry, I simply can’t ignore it!

I’m sorry to belabor the point but as a side note, one reason the alternative unit “kilocalorie” isn’t widely used is because in food science and nutrition the uppercase “Calorie” is commonly used to express the energy value of certain foods. For example, here in the States, package labels on most foods come with a nutrition facts section in which the number of Calories in the food is indicated per serving. This Caloric value is PRECISELY equal to 1000 lowercase calories. Simply put, in order to standardize the kilocalorie as a unit, all nutritional labels would have to switch from Calories to kilocalories. Again, it’s such a subtle inaccuracy that I’m really not complaining, I just couldn’t resist pointing it out as a learning opportunity.