**Answer:**

**a. **Rate constant: 1.2118x10⁻⁴ yrs⁻¹

**b. **The age of the object is 20750 years

**Explanation:**

**a. **We can solve the rate constant in an isotope decay by using Half-Life, as follows:

K = Ln 2 / Half-life

K = ln 2 / 5720 years =

<h3>1.2118x10⁻⁴ yrs⁻¹</h3><h3 />

**b. **The general equation of isotope decay is:

Ln [A] = -kt + Ln [A]₀

<em>Where [A] is concentration of the isotope after time t, </em>

<em>k is rate constant</em>

<em>and [A]₀ initial concentration of the isotope.</em>

<em />

Computing the values of the problem:

Ln [0.89x10⁻¹⁴] = -1.2118x10⁻⁴ yrs⁻¹t + Ln [1.1x10⁻¹³]

-2.5144 = -1.2118x10⁻⁴ yrs⁻¹t

20750 years = t

**The age of the object is 20750 years**

**<em />**