This item is very popular.

I asked the shop clerk where the product was.

I requested a refund because the product was defective.

The product was defective, so I asked the clerk to return the money.

He continued his journey to find the truth.

He started calculating to obtain the ratio of the two numbers.

I gave her a gift certificate.

Unexpectedly, his face came to mind.

This plan is impossible.

A mass noun refers to a noun that cannot be counted.