Al2(SO4)3 + BaCl2 BaSO4 + AlCl3

Hey there!

Al₂(SO₄)₃ + BaCl₂ → BaSO₄ + AlCl₃

First balance SO₄ since it is a polyatomic ion.

3 on the left, 1 on the right. Add a coefficient of 3 in front of BaSO₄.

Al₂(SO₄)₃ + BaCl₂ → 3BaSO₄ + AlCl₃

Balance Ba.

1 on the left, 3 on the right. Add a coefficient of 3 in front of BaCl₂.

Al₂(SO₄)₃ + 3BaCl₂ → 3BaSO₄ + AlCl₃

Balance Cl.

6 on the left, 3 on the right. Add a coefficient of 2 in front of AlCl₃.

Al₂(SO₄)₃ + 3BaCl₂ → 3BaSO₄ + 2AlCl₃

Balance Al.

2 on the left, 2 on the right. Already balanced.

Our final balanced equation:

Al₂(SO₄)₃ + 3BaCl₂ → 3BaSO₄ + 2AlCl₃

Hope this helps!

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m