1. All the food was gone.

2. All the food were gone.
3. All the foods was gone.
4. All the foods were gone.

(Which ones are grammatical? What kind of noun is 'food'? A countable noun or an uncountable noun? A material noun or a collective noun? Thank you.)

Only #1 is correct.

The word "food" is a non-count noun:
http://grammar.ccc.commnet.edu/grammar/noncount.htm

1. All the food was gone. (Grammatical)

2. All the food were gone. (Not grammatical; it should be "was" instead of "were.")
3. All the foods was gone. (Not grammatical; it should be "food" instead of "foods.")
4. All the foods were gone. (Grammatical)

The noun "food" is an uncountable noun. It refers to a substance that is consumed to maintain life and growth.

Out of the four sentences, sentence 1 is grammatically correct: "All the food was gone."

The noun "food" in this context is an uncountable noun because it refers to a substance that is generally not considered as separate individual items. Uncountable nouns are not pluralized and do not have a specific article for singular or plural forms. Examples of uncountable nouns include water, milk, sugar, etc.

In this case, "food" is also a material noun, as it refers to a substance that has a physical presence and is consumed for nourishment. Material nouns are typically uncountable, as they refer to substances rather than individual items or entities.

Collective nouns, on the other hand, are used to refer to groups or collections of people, animals, or things (e.g., team, family, flock). None of the given sentences use "food" as a collective noun.

Among the given sentences, only sentence 1, "All the food was gone," is grammatically correct.

The noun "food" is generally considered an uncountable noun. Uncountable nouns do not have a plural form, so sentences 2 and 4, which use the plural form "foods," are incorrect.

Furthermore, "food" is not a collective noun (which refers to a group of things or people), nor is it a material noun (which refers to a substance). Instead, it is a mass noun, also known as an uncountable noun.