Scale and measuring tape.
To determine the mass and volume, you can find the density. The block will float if its density is less than that of water.
Answer:
I Would bc it's the better opportunity
1st one= CaO +H2O=Ca(OH)2
product side-
Ca=1
O=2
H=2
Reactant side-
Ca=1
O=2
H=2
The first one is balanced for you
There is 1 calcium on each side 2 oxygens on each side and 2 hydrogens on each side
It becomes more stable
delta G gets closer to zero