First of try to find out which organic or inorganic compound formed after the composite fabrication through various characterization method. If it's not a newly fabricated compound you can get the final compound chemical structure also from various sources. Then calculate the mass and weight from that you can get your density by the well-known formula ρ = m/v

If you know mass and volume, it is possible to calculate.

Density (ρ) = Mass (m) / Volume (V)

Volume = depends on the geometry. V = length × width × height.

Jaymin Sanchaniya thank you, yes sir. I applied this formula. but I got less value than the theoretical measurement.

Wedad A. Alwesabi By any chance, is it porous material?

ZNCI2+CU(NO3)2.3H2O=ZNO+CUO+2HNO3+2HCI+O2+H2 RO=m/v