How many na+ ions are at least partially within the unit cell?

A unit cell is a simplest repeating unit in a crystal in which particle are freely vibrating

Sodium chloride having face centered cubic lattice in which sodium and chloride ion are arranged and vibrating.

The sodium ion are arranged on eight corners of the cube whereas they are also present on all the six centres of all six faces.

Thus, number of Na+ ion  

Hence total of 14 sodium ions are present in NaCl lattice.

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.

2b2t

explanation:

2b2t