Question

Wet paper does not burn while a dry paper catches fire easily. Why?

Answer 1

Wet paper have moisture in them . But in dry paper the moisture is not there and it is combustible to fire. 
a substance with moisture don't catch fire as water is a bad conductor of heat....

Answer 2

water is a bad conductor of heat, that why  a wet paper will not burn immediately, but a dry paper will catch fire immediately as there is no moisture in the paper