9) 3mgcl2 coefficient: ____________ subscript for mg: ____________ subscript for cl: ____________

Explanation:

Step1: Identify coefficient

The number in front of the chemical formula is the coefficient. Here, for $3MgCl_2$, the coefficient is 3.

Step2: Identify Mg sub - script

In the formula $MgCl_2$, the sub - script for Mg is 1. When no sub - script is written for an element in a chemical formula, it is assumed to be 1.

Step3: Identify Cl sub - script

In the formula $MgCl_2$, the sub - script for Cl is 2.

Answer:

coefficient: 3 Subscript for Mg: 1 Subscript for Cl: 2