A block has a volume of 0.07 m3 and a density of 3,500 kg/m3. What's the force of gravity acting on the block (and weight) in the air?

W = mass * acceleration

and the gravity acceleration is know as 9.81 m/s^2

so we need to calculate the mass,

from the givens, mass = density * volume

m = 3500*0.07 = 245 kg

subs. in W = m*g,

W = 245 * 9.81

W = 2403.45 N