Metal X displaces metal Y. Metal Z does not react with X or Y. What is the correct order of decreasing reactivity for metals X, Y, and Z?

Metals on top of the activity series can displace metals at the bottom and they are highly reactive as compared to metals at the bottom of the series.

Hence, the order is X>W>Y>Z.

the role of the microscope world in creating new materials .

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.