Answer
The magnitude of the impulse on the lizard is $~~0.0045~kg~m/s$
Work Step by Step
We can find the momentum of one foot just before each slap:
$p = m~v$
$p = (0.0030~kg)(1.50~m/s)$
$p = 0.0045~kg~m/s$
The magnitude of the impulse on the lizard must be equal in magnitude to the initial momentum of the foot.
The magnitude of the impulse on the lizard is $~~0.0045~kg~m/s$
