a bigger one

[Akasaka]

Hello everyone,
Is this sentence correct? Is it all right if I use "a" here? The indefinite article and the pronoun "one" seem to be similar to me.

This cap is too small for me. Show me a bigger one.

English is very difficult for me. Every time I write an English sentence by myself, I have to ask if it is correct or not.

Thanks in advance.

 

[bibliolept]

The two sentences are grammatically correct and idiomatic.

If you rewrote the sentence as "Show me one that is bigger," the "one" might not seem so puzzling.

 

[Outsider]

Is this sentence correct? Is it all right if I use "a" here?
This cap is too small for me. Show me a bigger one.

The indefinite article and the pronoun "one" seem to be similar to me.

They can mean the same, but here we add "one" after "a bigger" to turn it into a (pro)noun.