Answer:

Explanation:
(a) Balanced equation
Cu + 2AgNO₃ ⟶ Cu(NO₃)₂+ 2Ag
(b) Calculation
You want to convert atoms of Cu to atoms of Ag.
The atomic ratio is ratio is 2 atoms Ag:1 atom Cu

C. CaCl2 is the correct answer
<span>pm stands for picometer and picometers are units which can be used to measure really tiny distances. One picometer is equal to 10^{-12} meters. We know that one centimeter is equal to 10^{-2} m so there are 10^2 cm per meter.
We can change the distance d = 115 pm to units of centimeters.
d = (115 pm) x (10^{-12}m / pm) x (10^2 cm / m)
d = 115 x 10^{-10} cm = 1.15 x 10^{-8} cm
The distance in centimeters is 1.15 x 10^{-8} cm</span>
This
electronic transition would result in the emission of a photon with the highest
energy:
4p
– 2s
<span>This
can be the same with the emission of 4f to 2s which would emit energy in the
visible region. The energy in the visible region would emit more energy than in
the infrared region which makes this emission to have the highest energy.</span>