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Chemistry Question 123 – AP-EAMCET 2026

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Observe the following pairs of elements I. P, H II. C, S III. N, Cl Which pairs contain the elements having same electronegativity?

Electronegativity is a measure of the tendency of an atom to attract a shared pair of electrons (or electron density) towards itself when it forms a chemical bond. It generally increases across a period and decreases down a group in the periodic table.

Step 1: Understand Electronegativity and its Trends✦ Active

Electronegativity is a chemical property that describes the tendency of an atom to attract electrons towards itself in a chemical bond. On the Pauling scale, values generally range from about 0.7 (for Francium) to 3.98 (for Fluorine). Electronegativity increases from left to right across a period and decreases from top to bottom down a group in the periodic table. Elements with very similar electronegativities often form covalent bonds with minimal polarity, or their bond polarities are very close.

Step 2: Recall/Lookup Electronegativity Values○ Expand

It's important to know or look up the electronegativity values for the given elements on the Pauling scale:

* Hydrogen (H): 2.20

* Phosphorus (P): 2.19

* Carbon (C): 2.55

* Sulfur (S): 2.58

* Nitrogen (N): 3.04

* Chlorine (Cl): 3.16

💡 Teacher's Secret Hint

Remember that these values are averages and can vary slightly depending on the source or the specific bonding environment, but the relative order and closeness remain consistent.

Step 3: Compare Electronegativities for Each Pair○ Expand

Now, let's compare the electronegativity values for each pair and calculate the absolute difference:

**Pair I (P, H):**

Electronegativity of P = 2.19

Electronegativity of H = 2.20

Difference = |2.19−2.20|=0.01. This is a very small difference, indicating very similar electronegativities.

**Pair II (C, S):**

Electronegativity of C = 2.55

Electronegativity of S = 2.58

Difference = |2.55−2.58|=0.03. This is also a very small difference, indicating similar electronegativities.

**Pair III (N, Cl):**

Electronegativity of N = 3.04

Electronegativity of Cl = 3.16

Difference = |3.04−3.16|=0.12. While larger than the previous two differences, a difference of 0.12 is often considered 'similar' in a broader chemical context, especially when discussing bond character or comparing to larger electronegativity differences. Given the options, it is implied that this difference is considered sufficient for the elements to have 'same' or very similar electronegativity.

💡 Teacher's Secret Hint

A common rule of thumb is that if the electronegativity difference is less than about 0.4, the bond is considered nonpolar covalent. If it's between 0.4 and 1.7, it's polar covalent. If it's greater than 1.7, it's ionic. For 'same' electronegativity, we are looking at much smaller differences.

Step 4: Identify Pairs with Similar Electronegativity○ Expand

Based on the comparison in Step 3, all three pairs (P, H; C, S; and N, Cl) have electronegativity values that are considered sufficiently similar or 'same' within the context of this question.

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