The missing question is:
<em>What is the percent efficiency of the laser in converting electrical power to light?</em>
The percent efficiency of the laser that consumes 130.0 Watt of electrical power and produces a stream of 2.67 × 10¹⁹ 1017 nm photons per second, is 1.34%.
A particular laser consumes 130.0 Watt (P) of electrical power. The energy input (Ei) in 1 second (t) is:

The laser produced photons with a wavelength (λ) of 1017 nm. We can calculate the energy (E) of each photon using the Planck-Einstein's relation.

where,

The energy of 1 photon is 6.52 × 10⁻²⁰ J. The energy of 2.67 × 10¹⁹ photons (Energy output = Eo) is:

The percent efficiency of the laser is the ratio of the energy output to the energy input, times 100.

The percent efficiency of the laser that consumes 130.0 Watt of electrical power and produces a stream of 2.67 × 10¹⁹ 1017 nm photons per second, is 1.34%.
You can learn more about lasers here: brainly.com/question/4869798
<u>Given:</u>
Initial temperature, T1 = 20 C
Final temperature, T2 = 40 C
<u>To determine:</u>
The temperature change
<u>Explanation:</u>
Convert degree C to Kelvin
Temperature in Kelvin = degree C + 273
T1 = 20 + 273 = 293 K
T2 = 40 + 273 = 313 K
Incremental temperature change = T2 - T1 = 313-293 = 20 K
Ans: The temperature change in kelvin is 20 K
The average atomic mass of the imaginary element : 47.255 amu
<h3>Further explanation </h3>
The elements in nature have several types of isotopes
Isotopes are elements that have the same Atomic Number (Proton)
Atomic mass is the average atomic mass of all its isotopes
Mass atom X = mass isotope 1 . % + mass isotope 2.% ..
isotope E-47 47.011 amu, 87.34%
isotope E-48 48.008 amu, 6.895
isotope E-49 50.009 amu, 5.77%
The average atomic mass :

Answer:
The answer to your question is 32.44 moles
Explanation:
Data
moles of Na₂CO₃ = ?
volume = 9.54 l
concentration = 3.4 M
Formula
Molarity = 
Solve for number of moles
number of moles = Molarity x volume
Substitution
Number of moles = (3.4)( 9.54)
Simplification
Number of moles = 32.44