A scoop of icecream(100g) has an energy value of 775 000 joules. what is this value in Calories?

Just divide the joules by 4.184 joules/cal to get calories. Now, notice that your answer choices are in Calories (with an upper case C). Those are "nutritional calories" rather than "chemical calories". A nutritional calorie is 1000 chemical calories, so divide your original answer by 1000 to get nutritional calories.