Answer:
3.2L
Explanation:
PV=nRT
since pressure and temperature are held constant we have V=nR
R is a constant also,
Thus; 
v1=1.5L , n1=3mol, n2=1.4mol

v2=
v2=3.2L
It will sink below the surface. Since dish soap is a surfactant, it will alter the water's surface tension. Lowering the surface tension, the water will no longer be able to support the mass of the twig.
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