Noble gases have complete valence electron shells
Explanation:
Mole = 0.5 = n/NA
n = no. of molecule
NA = avogadro number = 6.023x 10^23
so
N/NA = 0.5
N = 0.5 x 6.023 x 10^23
N = 3.0115 x 10^23
To make clay float in water you have to shape it into something wide enough and roughly bowl-shaped so that it can displace enough water to compensate for its mass, just like a real boat.