30me!
which is greater, the atomic radius of krypton (kr), or the ionic radius of strontium cation (sr^2+)? justify your answer in terms of nuclear charge, effective nuclear charge (z_eff), number of principle energy levels, and the shielding effect.

energy to lift something =

                (mass of the object) x (gravity) x (height of the lift).

but

this simple formula only works if you use the right units.

mass . . kilograms
gravity . . meters/second²
height . . meters

for this question . .

mass = 55 megagram = 5.5 x 10⁷ grams = 5.5 x 10⁴ kilograms

gravity (on earth) = 9.8 m/second²

height = 500 cm  =  5.0 meters

so we have

energy = (5.5 x 10⁴ kilogram) x (9.8 m/s²) x (5 m)

            =  2,696,925 joules .

that's quite a large amount of energy equivalent to
straining at the rate of 1 horsepower for almost exactly an
hour, or burning a 100 watt light bulb for about 7-1/2 hours.

the reason is the large mass that's being lifted.
on earth, that much mass weighs about 61 tons.

Copper, silver, aluminum, cobalt, chromium, mercury