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JEE Main Chemistry Structure of Atom 2026 JEE Main 2026 (23 January Shift 2)

JEE Main Chemistry Question (2026) — Solution

Question

Identify the INCORRECT statements from the following: A. Notation _ 12 ^ 24 Mg represents 24 protons and 12 neutrons. B. Wavelength of a radiation of frequency 4.5 10^ 15 ~s ^ -1 is 6.7 10^ -8 ~m . C. One radiation has wavelength = _ 1 (900 ~nm ) and energy = E _ 1 . Other radiation has wavelength = _ 2 (300 ~nm ) and energy = E _ 2 . E _ 1 : E _ 2 =3: 1. D. Number of photons of light of wavelength 2000 pm that provides 1 J of energy is 1.006 10^ 16 . Choose the correct answer from the options given below:

Options

  1. A. B and C Only
  2. B. A and D Only
  3. C. A and C Only
  4. D. A and B Only

Answer

C. A and C Only

Step-by-step solution

Checking each statement: (A) states _ 12 ^ 24 Mg has 24 protons, but the mass number is 24 and atomic number is 12, so this is INCORRECT. (B) Using = c f = 3 10^8 4.5 10^ 15 = 6.67 10^ -8 m, which is CORRECT. (C) For _1 = 900 nm and _2 = 300 nm, since energy is inversely proportional to wavelength, E_1:E_2 = 1:3, not 3:1 as stated, so this is INCORRECT. (D) For photons at = 2000 pm, energy per photon is E = hc = 9.94 10^ -17 J, giving N = 1.006 10^ 16 photons for 1 J, which is CORRECT. The incorrect statements are A and C.

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