Question
Q4. Which element has a first ionisation energy lower than that of sulfur? A Chlorine B Oxygen C Phosphorus D Selenium
Answer
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(228 Votes)
Scarlett
Master · Tutor for 5 years
Answer
Option: D. Selenium has first ionization energy lower than that of Sulfur.
Explanation
## Step1: Ionization energy is the energy required to remove an electron from a gaseous atom or ion. The trend in ionization energy in the Periodic Table is that it generally increases as we move across each period (row) from left to right due to a filling shell having greater effective nuclear charge, and decreases as we move down each group (column) due to outermost electrons being stationed further from the nucleus.## Step2:For this question, we need to look at the first ionization energy values for the provided elements:- Chlorine (Cl): 1251.2 kJ/mol- Oxygen (O): 1313.9 kJ/mol- Phosphorus (P): 1011.8 kJ/mol- Selenium (Se): 940.9 kJ/mol- Sulfur (S): 1000.0 kJ/mol## Step3:Selenium (Se) has the first ionization energy lower than that of Sulfur (S), which means it is easier for Selenium (Se) to lose an electron to become positive ion.## Step4:If you look back at the options stated in the question, you will find that Selenium (Se) is one of those options.