Gravity. The rock is being pushed down and you are counteracting that force with a crowbar pushing it upward.
srry the pic is not clear......
l cant see it.....
Wavelength of the light is 2.9 × 10⁻⁷ m.
<u>Explanation:</u>
Planck - Einstein equation shows the relationship between the energy of a photon and its frequency, and they are directly proportional to each other and it is given by the equation as E = hν,
where E is the energy of the photon
h is the Planck's constant = 6.626 × 10⁻³⁴ J s
ν is the frequency
From the above equation, we can find the frequency by rearranging the equation as,
ν =
= 
Now the frequency and the wavelength are in inverse relationship with each other.
ν × λ = c
It can be rearranged to get λ as,
λ = c / ν
= 
So wavelength is 2.9 × 10⁻⁷ m.
1.Calcium Chloride
2.Lithium Bromide
3.Beryllium Sulfide
4.Lithium Fluoride
5. Potassium hydroselenide
6. Strontium phosphide
7.Barium Chloride
8.Iron Oxide
9.Iron
10.?
11.Copper Nitride
I would say A and D. A is right for sure, as for D, I'm not so sure. Hope this helps!