Explanation:
When AgNO3 solution is added in excess to 1 M solution of CoCI3.xNH3, one mole of AgCI is formed. From this information, we can determine the value of x.

Step 1: Write the balanced chemical equation for the reaction between AgNO3 and CoCI3.xNH3.

AgNO3 + CoCI3.xNH3 → AgCI + Co(NH3)6 3+

Step 2: Determine the number of moles of AgNO3 needed to react with one mole of CoCI3.xNH3.

From the balanced chemical equation, we can see that one mole of AgNO3 reacts with one mole of CoCI3.xNH3 to form one mole of AgCI. Therefore, the number of moles of AgNO3 needed to react with one mole of CoCI3.xNH3 is 1.

Step 3: Determine the number of moles of CoCI3.xNH3.

Since the solution is 1 M, we know that there is one mole of CoCI3.xNH3 per liter of solution. Therefore, the number of moles of CoCI3.xNH3 in the solution is also 1.

Step 4: Determine the value of x.

From step 2, we know that one mole of AgNO3 reacts with one mole of CoCI3.xNH3 to form one mole of AgCI. Since we have one mole of AgCI formed, we know that one mole of CoCI3.xNH3 must have been present in the solution. Therefore, we can use the number of moles of CoCI3.xNH3 (which we determined in step 3) to calculate the value of x.

1 mole of CoCI3.xNH3 = 1 mole of Co(NH3)6 3+

Therefore, the coordination number of CoCI3.xNH3 is 4, since there are 4 NH3 ligands coordinated with the cobalt ion.