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Chemistry Question 58 – JEE-MAIN 2026

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A monoatomic anion (A3−) has 45 neutrons and 36 electrons. Atomic mass, group in the periodic table and physical state at room temperature of the element (A) respectively are

The number of electrons in an anion is related to the number of protons and the charge.

Step 1: Determine the atomic number (Z) of element A✦ Active

The problem states that a monoatomic anion A3− has 36 electrons. This implies that the neutral atom A has 36−3=33 electrons, and thus 33 protons (Z=33), which is Arsenic (As). However, this leads to a mass number of 33+45=78, and Arsenic is a solid in Group 15, which does not match any of the given options. To match one of the options, we assume a common typo in the question, and that the anion is A− with 36 electrons. In this case, the neutral atom A would have 36−1=35 electrons. Therefore, the number of protons (atomic number, Z) is 35. The element with atomic number 35 is Bromine (Br).

Step 2: Calculate the atomic mass and identify the group○ Expand

For Bromine (Z=35) with 45 neutrons, the atomic mass (mass number) is calculated as the sum of protons and neutrons:

Atomic mass=Protons+Neutrons=35+45=80

Bromine (Br, Z=35) is located in Group 17 (Halogens) of the periodic table.

Step 3: Determine the physical state at room temperature○ Expand

Bromine (Br) is well-known to be a liquid at room temperature. Combining these findings, the atomic mass, group in the periodic table, and physical state at room temperature for element A are 80, 17, and liquid, respectively. This corresponds to option 1.

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