Define each periodic table trend?

organisms are more likely to be more preserved in mud than sand because mud is moist and wet, while sand is very dry.

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

a electronegativity decreases beacuse the size of nucleus is bigger.