Answer: The hydroxide ion concentration in aqueous solution is

Step-by-step explanation:
To calculate the hydroxide ion concentration, we use the equation:
![pOH=-\log[OH^-]](https://img.qammunity.org/2019/formulas/chemistry/high-school/ur2f3m6zoirj5p05ac4nknmpiip97f0mi9.png)
We are given:
pOH = 9.85
Putting values in above equation, we get:
![9.85=-\log[OH^-]](https://img.qammunity.org/2019/formulas/chemistry/high-school/1qjjdvq1czm61x5xanj9nex3xasxvsrsao.png)
![[OH^-]=10^(-9.85)=1.412* 10^(-10)M](https://img.qammunity.org/2019/formulas/chemistry/high-school/jjb56em010wj3nwbkwrsqnp9lluuoj72ks.png)
Hence, the hydroxide ion concentration in aqueous solution is
