The word "river" is countable, meaning you can have one river, two rivers, etc. It refers to individual bodies of flowing water, each of which can be distinctly identified and enumerated. In contrast, "water" is an uncountable noun, as it refers to a substance that cannot be counted individually without a unit of measurement.
uncountable
Uncountable
uncountable
Transport is both countable and uncountable as a noun.
The noun 'steel' is an uncountable (mass) noun, a word for a substance.
The noun 'daytime' is an uncountable noun.
The word 'violence' is an uncountable noun.
The noun 'health' is an uncountable noun, a word for a condition.
"Bun" can be both countable and uncountable. For example, you can say "I bought five buns" or "I would like some bun with my soup."
Yes, the noun 'hydrogen' is an uncountable noun, a word for a substance.
It is uncountable. Can you have 3 food? No. The best way to check is to compare it to money and dollars. Money is uncountable and dollars is countable. I can have 3 dollars, but not 3 money.
The noun 'steel' is an uncountable (mass) noun, a word for a substance.