The phenomenon you're experiencing is due to the difference in the freezing temperatures and composition of the items in your freezer, including ice cream.
Freezer temperature: Your freezer is set to a low temperature to keep items frozen. The temperature is typically well below the freezing point of water (0 degrees Celsius or 32 degrees Fahrenheit). This extreme cold ensures that most foods and liquids freeze solid.
Water-based items: Most of the items in your freezer, such as fruits, vegetables, meat, and other liquids, contain a significant amount of water. Water freezes at 0 degrees Celsius (32 degrees Fahrenheit), turning into a solid state, which is why they become "rock hard" when frozen.
Ice cream composition: Ice cream is a frozen dessert made from a mixture of milk or cream, sugar, flavorings, and sometimes egg yolks. It also contains air, which is incorporated during the churning process. Unlike most other items in your freezer, ice cream has a lower freezing point due to its composition. The sugar and other additives in ice cream act as freezing point depressants, meaning the mixture freezes at a lower temperature than plain water. This prevents it from becoming as hard as a solid block of ice, allowing it to maintain a softer, scoopable texture.
Freezer location: The location of items in your freezer can also play a role. The items closest to the freezer's cooling element or on the shelves near the vents will freeze faster and might become harder compared to items placed farther away from these colder areas.
In summary, your freezer is kept at a very low temperature to freeze items solid. Water-based items, like fruits, vegetables, and other liquids, freeze at 0 degrees Celsius (32 degrees Fahrenheit), resulting in a "rock hard" texture. Ice cream, on the other hand, has a lower freezing point due to its composition, so it maintains a softer texture, making it easier to scoop.