Answer
a. No
b. Not plausible
Work Step by Step
a. The density of gold is much higher than sand so the weight of sand of same volume will be much lower which will trigger the booby trap.
b. Volume = 1L = 1000 cm$^{3}$
mass of idol = density $\times$ volume = 19.36 * 1000 = 19360 g
It is not plausible to play catch with an idol of approximately 20 kg.
