<h3>Given equation:-</h3>
<h3>BALANCED EQUATION:-</h3>
We have to distinguish a solution of sodium sulphite from a solution of sodium sulphate in the laboratory.
Solution of sodium sulphite is acidified with dilute HCl and to that when few drops of barium chloride (BaCl₂) solution is added, white precipitate is formed. The white precipitate is soluble in HCl.
To this solution 2 drops of iodine (I₂) solution is added and brown colour of iodine is discharged as I₂ gets reduced to HI.
The reactions involved in case of sodium sulphite is are:
Na₂SO₃ + BaCl₂ = BaSO₃ ↓ + 2NaCl
(white precipitate)
BaSO₃ + 2HCl = BaCl₂ + H₂SO₃
H₂SO₃ + I₂ + H₂O = H₂SO₄ + 2HI
On the other hand, solution of sodium sulphate is acidified with dilute HCl and to that when few drops of barium chloride (BaCl₂) solution is added, white precipitate is formed. The white precipitate of BaSO₄ is formed which is insoluble in HCl.
Na₂SO₄+ BaCl₂ = BaSO₄ ↓ + 2NaCl
(white precipitate)
Redshift is said to be experienced when the light or any other electromagnetic radiations from an object undergo an increase in the wavelength but it does not mean that the light literally becomes red.
Redshift occurs due to the expansion of space. It means the farther away the galaxy is from us, the more space it has expanded in the time.
Because as the light left the galaxy, more of the light has been stretched and so more redshifted the light is.