Step 1: List the given values.
[tex]\begin{aligned} & W = 6.93 \times 10^{-19} \: \text{J} \\ & f = 2.50 \times 10^{15} \: \text{s}^{-1} \end{aligned}[/tex]
Step 2: Calculate the energy of a photon.
[tex]\begin{aligned} E & = hf \\ & = (6.626 \times 10^{-34} \: \text{J}\cdot\text{s})(2.50 \times 10^{15} \: \text{s}^{-1}) \\ & = 1.6565 \times 10^{-18} \: \text{J} \end{aligned}[/tex]
Step 3: Calculate the kinetic energy.
[tex]\begin{aligned} KE & = E - W \\ & = 1.6565 \times 10^{-18} \: \text{J} - 6.93 \times 10^{-19} \: \text{J} \\ & = 9.635 \times 10^{-19} \: \text{J} \\ & \approx \boxed{9.64 \times 10^{-19} \: \text{J}} \end{aligned}[/tex]
Hence, the kinetic energy of the ejected electrons is 9.64 × 10⁻¹⁹ J.
[tex]\\[/tex]
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