Answer:
The third and the fourth option.
![3Mg+1Fe_2O_3 \\ = 3MgO + 2Fe[tex]3Mg+1Fe_2O_3 \\ = 3MgO + 2Fe \\](https://tex.z-dn.net/?f=3Mg%2B1Fe_2O_3%20%5C%5C%20%20%3D%203MgO%20%2B%202Fe%3C%2Fstrong%3E%3C%2Fp%3E%3Cp%3E%3Cstrong%3E%5Btex%5D3Mg%2B1Fe_2O_3%20%5C%5C%20%20%3D%203MgO%20%2B%202Fe%20%5C%5C%20)

Explanation:
The number of products and reactants are balanced
Answer:
No,
Although the atmosphere is mostly made up of nitrogen, it is in the form of gas known as dinitogen N2. Plant cannot use this form.
Explanation:
The answer is;
a. add electric current.
b. add buffer solution
The process of gel electrophoresis taps on the property of net charges of molecules to ensure that they travel up the gel. Additionally, the buffer acts as the mobile phase for the molecules and also give molecules net charge as they travel through the gel. It is until the molecules reaches an isoelectric point,where the molecule has zero net charge, that they stops moving through the gel. This is how bands are formed.