A sample of an unknown material weighs 260 N in air and 175 N when immersed in alcohol of specific gravity 0.700.

Answer 1

rho g volume = weight of fluid displaced

0.7 * 1000 kg/m^3 * 9.8 * V = 260-175 = 85
so
V = .0124 m^3 fluid displaced

mass = 260/9.8 = 26.5

density = mass/volume = 2139 kg/m^3
or specific gravity of 2.14

maybe concrete or some rock