If the length of a copper wire is increased by twice, then its resistivity will be

Resistivity (ρ) is an intrinsic property of a material that depends only on the nature of the material and its temperature, not on the dimensions (length, area, or volume) of the conductor. So if the length of a copper wire is doubled, the resistivity remains the same. However, the resistance (R = ρL/A) would change because resistance depends on length and cross-sectional area. The distinction between resistivity (material property) and resistance (geometric property) is important.