Elements and compounds are usually more dense in their solid than in their liquid state. However, water is one of the notable exceptions. The density
of ice is 0.917 g/mL, while the density of liquid water is 1.00 g/mL. What
natural phenomena does this explain?

Explanation:

The molecules in water is more tightly packed than in ice, so water has greater density than ice.

i'm not sure

explanation:

i'll try whatever you got

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer