The uploaded PDF is a Class 11 Chemistry worksheet on the Structure of Atom, prepared mainly for NEET and other competitive exam aspirants. It contains 75 multiple-choice questions with detailed explanations, strictly based on NCERT theory. The questions cover atomic models, electromagnetic radiation, Bohr’s theory, quantum numbers, electronic configuration, spectra, photoelectric effect, and wave–particle duality. The worksheet is designed to test both numerical accuracy and conceptual clarity.

I am writing about this worksheet because the Structure of Atom chapter forms the foundation of physical chemistry and often decides early confidence in NEET preparation. Many students struggle with formulas, constants, and interpretation-based questions. Analysing this worksheet helps identify exactly how NCERT concepts are converted into exam questions and which areas need repeated revision to avoid common mistakes.

Overall Pattern of the Worksheet

The worksheet follows a pure MCQ format with solutions, making it suitable for self-practice and concept reinforcement. Questions range from simple definition-based to calculation-intensive ones involving Planck’s equation, Rydberg formula, and Bohr’s energy expressions. The difficulty level is easy to moderate, matching NEET standards rather than advanced Olympiad level.

Atomic Models and Their Limitations

Several questions test understanding of early atomic models. The worksheet highlights:

• Limitations of Rutherford’s atomic model
• Why Bohr introduced fixed energy orbits
• Stability of atoms explained using quantised energy levels

Students are expected to know not just the models, but also why earlier theories failed and how later models improved upon them.

Electromagnetic Radiation and Photon Energy

A large portion of the worksheet focuses on electromagnetic radiation. Questions involve:

• Calculation of photon energy using Planck’s equation
• Relationship between wavelength, frequency, and energy
• Identification of visible, ultraviolet, and infrared regions

These questions reinforce that shorter wavelength means higher energy, a concept frequently tested in NEET.

Download this Structure of Atom PDF File: Click Here

Hydrogen Spectrum and Rydberg Equation

The worksheet includes multiple questions on hydrogen emission spectra, covering:

• Lyman, Balmer, Paschen, Brackett, and Pfund series
• Transitions responsible for visible and ultraviolet lines
• Use of Rydberg’s equation to calculate wavelength and wave number

Students must clearly remember which series belongs to which region of the electromagnetic spectrum.

Bohr’s Theory and Energy Calculations

Bohr’s postulates are repeatedly tested through numerical questions such as:

• Energy of electrons in different orbits
• Radius of Bohr orbits
• Energy released or absorbed during electronic transitions

The worksheet reinforces that energy is inversely proportional to the square of the principal quantum number, an idea that appears frequently in exams.

Quantum Numbers and Electronic Configuration

A significant section focuses on quantum numbers and orbital concepts, including:

• Allowed values of n, l, ml, and ms
• Number of orbitals and electrons in a shell
• Identification of subshells like 3p, 4f, and 3d

Questions also test Aufbau principle, Hund’s rule, and stability of half-filled and fully-filled orbitals.

Wave–Particle Duality and Modern Physics Concepts

The worksheet covers modern atomic theory through questions on:

• de Broglie wavelength
• Heisenberg’s uncertainty principle
• Photoelectric effect
• Dual nature of radiation and matter

These questions test conceptual understanding rather than rote learning and often confuse students if basics are not clear.

Spectra, Experiments, and Important Discoveries

Important experiments and effects are also included, such as:

• Photoelectric effect
• Stark effect and Zeeman effect
• Millikan’s oil drop experiment
• Cathode ray experiments

Such questions are straightforward but require precise factual recall, especially for one-mark NEET questions.

What This Worksheet Teaches NEET Aspirants

From this worksheet, students clearly learn that:

• NCERT theory is sufficient if understood properly
• Formula-based questions require careful unit conversion
• Quantum number rules are non-negotiable
• Repeated practice reduces calculation errors

The worksheet also shows how similar concepts are tested in different numerical forms.