Answer:- 
Solution:- Wavelength is given and we are asked to calculate the frequency. The equation that correlates frequency with wavelength is:

where,
is the symbol for frequency, c is the symbol for speed of light and
is the symbol for wavelength.
Speed of light is
and the wavelength is given as
.
Let's plug in the values in the equation and so the calculations to calculate the frequency:


(since,
)
So, the frequency of the wave is
.
The solid portion of a comet—the only portion that exists when the comet is far from the Sun.
The answer is A. Hope this helped
Answer:
The percentage by mass of benzene in the solution is approximately 0.2%
Explanation:
The given parameters are;
The mass of the benzene solute dissolved in the gasoline solvent, m₁ = 1.56 g
The total volume of the benzene gasoline solution made, V = 998.44 mL
The density of gasoline, ρ = 0.7489 g/mL
Mass, m = Density, ρ × Volume, V
∴ The mass of gasoline in the 998.44 mL, solution = 0.7489 g/mL × 998.44 mL = 747.731716 g
The total mass of the solution = The mass of the benzene in the solution + The mass of the gasoline in the solution
∴ The total mass of the solution = 747.731716 g + 1.5 g = 749.231716 g

The percentage by mass of benzene in the solution = (1.5 g/749.231716 g)×100 ≈ 0.2% by mass.