Learn Italian: Questo ragazzo è più falso che sincero. - This boy is more fake than sincere.

In Italian, you use che when comparing two adjectives (falso and sincero) that describe the exact same subject (Questo ragazzo). You only use di when comparing two different subjects, like saying one boy is taller than another boy.

Do falso and sincero have to agree with the subject?

Yes! Both are adjectives describing Questo ragazzo, which is a masculine singular noun, so they both end in -o. If we were talking about a girl (Questa ragazza), the sentence would change to più falsa che sincera.

Can falso be used for people as well as objects?

Yes. While it means "fake" or "false" for objects (like a fake watch or a false answer), when used to describe a person, it means they are two-faced, deceitful, or insincere.

Why isn't there an article before Questo ragazzo?

Demonstrative adjectives like questo (this) and quello (that) take the place of the definite article (il, la, etc.). You never say il questo ragazzo, just questo ragazzo.