Are certificates required for listing activities in the Common App ?

Do I have to attach certificates/proof for the activities that I list out in the Common App?
If so, how can I do it? By scanning the certificate?

Thanks,
WhiteFlameAB

No. If/when the college wants verification, they will ask for it.

Then, how can colleges verify if the applicant is lying or not?

Often, the teacher and/or the GC will mention some of the EC’s in their recs. If multiple students apply to the same school and all claim to be president of the same club, you can assume the college will contact the GC. Additionally, the more prestigious/exclusive the EC/award, the greater the risk that the AO will google it.