Well if the change is reversible then it is a physical change, but if not then it is a chemical change.
A homogeneous mixture is made up of multiple different substances. (You can see different parts)
Ex: Cereal in milk or ice in soda
A heterogeneous mixture is a mixture that is mixed well. ( you can’t see the different parts)
Ex: Rain or air
Explanation:
a) Using Beer-Lambert's law :
Formula used :

where,
A = absorbance of solution = 0.945
c = concentration of solution = ?
l = length of the cell = 1.20 cm
= molar absorptivity of this solution =


(
)
14.16 μM is the molarity of the red dye solution at the optimal wavelength 519nm and absorbance value 0.945.
b) 
1 L of solution contains
moles of red dye.
Mass of
moles of red dye:



c) In order to dilute red dye solution by 5 times, we will need to add 1 L of water to solution of given concentration.
Concentration of red dye solution = 
Concentration of red solution after dilution = c'



The final concentration of the diluted solution is 
Answer: The number of grams of
in 1620 mL is 1.44 g
Explanation:
According to ideal gas equation:

P = pressure of gas = 1 atm (at STP)
V = Volume of gas = 1620 ml = 1.62 L (1L=1000ml)
n = number of moles = ?
R = gas constant =
T =temperature =


Mass of hydrogen =
The number of grams of
in 1620 mL is 1.44 g
Answer:
223.5 g
Explanation:
The formula between the number of moles, mass and Mr can be used to convert moles to grams.
<em>Number of moles = mass ÷ Mr</em>
So, mass = number of moles × Mr
Mr of Li₂O = (6.9 × 2) + 16 = 29.8
∴ Mass = 7.5 × 29.8 = <u>223.5 g</u>