Answer:
Density, 
Explanation:
Given that,
Mass of a flask is 450 g
Volume of benzene added to the flask is 145 mL or 145 cm³
The weight of the flask and benzene is found to be 754 g.
We need to find the density of the benzene.
Weight of benzene added = total weight of flask and benzene-mass of flask
m = 754 g - 450 g
m = 304 g
Density = mass/volume
So,

So, the density of the benzene is
.
Answer:
The answer is

Explanation:
The wavelength of the electromagnetic
radiation can be found by using the formula

f is the frequency
c is the speed of light
From the question we have

We have the final answer as

Hope this helps you
Molality is defined as the number of moles of solute in 1 kg of solvent.
molality of solution to be prepared is 0.50 molal
this means that in 1000 g of water there should be 0.50 mol of NaCl
if 1000 g of water should contain - 0.50 mol
then 750.0 g of water requires - 0.50 mol/kg x 0.750 kg = 0.375 mol
mass of NaCl in 0.375 mol - 58.5 g/mol x 0.375 mol = 21.9 g
therefore a mass of 21.9 g of NaCl is required