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class 12 physics Chapter 20: Atomic Spectra MCQs With Explanations

Practice class 12 physics Chapter 20: Atomic Spectra MCQs with explanations for Pakistani board exams. Includes solved objective questions, answer checking, chapter revision guidance and next chapter suggestions.

MCQs / class 12 / physics / Chapter 20: Atomic Spectra
10 MCQs

Chapter 20: Atomic Spectra Objective Preparation

Use this page for direct chapter practice, answer checking and explanation review. It is available through the clean URL shown in the browser, so students can bookmark and share this exact chapter.

10Total MCQs
10With explanations
1Topics represented

Topics found: Nuclear Physics

Atomic Spectra MCQs With Explanations

Q1. Radiation from radioactive element is:
Ionizing radiation such as alpha, beta, and gamma rays is invisible to the human eye and requires detectors for observation.
Q2. Thyroid cancer caused by:
I-131 is absorbed by the thyroid gland and can cause DNA damage leading to thyroid cancer due to its beta and gamma emissions.
Q3. 1 amu = ? MeV:
1 atomic mass unit (amu) equals approximately 931.5 MeV/c², derived from Einstein’s mass-energy equivalence.
Q4. Fissile with slow neutrons:
U-235 is fissile with thermal (slow) neutrons and sustains chain reactions in nuclear reactors.
Q5. The rate of radioactive decay of a sample is:
Radioactive decay follows first-order kinetics, where the decay rate is constant and proportional only to the number of undecayed nuclei.
Q6. Which particle is similar to an electron in charge and mass?
Beta particles are high-energy electrons (or positrons) emitted during beta decay, making them identical in charge and mass to electrons.
Q7. The correct relation for binding energy is:
Binding energy is given by Einstein’s mass-energy equivalence: E = Δm c², where Δm is the mass defect.
Q8. After two half-lives, decayed nuclei fraction:
After two half-lives, 75% (3/4) of the original nuclei have decayed, leaving 25% undecayed.
Q9. U-238 + n → ___ after beta emission:
U-238 captures a neutron to form U-239, which undergoes two beta decays to become Pu-239.
Q10. Color television tubes (CRTs) primarily emit:
CRTs accelerate electrons that strike phosphors, producing visible light; however, bremsstrahlung from electron deceleration generates low-energy X-rays as a byproduct.

After Chapter 20: Atomic Spectra, Practice Next Chapters

Once you finish these MCQs, continue with the next available chapters from physics so your revision stays chapter-wise and complete.

Chapter 20: Atomic Spectra Revision Guide

Complete the MCQs first, then review every incorrect answer against the textbook heading where that concept appears. For biology and other science subjects, pay attention to terminology, diagrams, sequence of processes, examples and differences between similar structures or functions.

This chapter page keeps the exact class, subject, chapter, question count, answer checking, explanations and follow-up chapters together, so students can revise from one focused URL instead of searching through the full book again.

class 12 Physics MCQ Preparation: Atomic Spectra

This page supports Intermediate Part 2 practice in Physics. At this stage, the main purpose is consolidating advanced concepts while balancing board revision, college assessments and admission preparation. The questions available here should be used with the current textbook and the instructions issued by the learner's school or examination board.

What Physics MCQs can test

In Physics, objective questions commonly draw on definitions, physical quantities, SI units, laws, graphs, diagrams, formulas and the interpretation of numerical situations. A useful answer is based on the exact wording and concept, not simply on recognising a familiar option. For this subject, learners should write the known quantities and units before choosing a formula, and distinguish a law from the example used to demonstrate it.

Atomic Spectra: what to focus on

Particles, structures, symbols, trends, equations, reaction conditions and the reasons substances behave differently.

Write the relevant symbol, structure or balanced equation and compare each option with the rule demonstrated by it.

Common mistakes for class 12 learners

In this subject, frequent errors include mixing scalar and vector quantities, overlooking units, reversing cause and effect, or choosing a familiar formula without checking its conditions. Pay special attention to links between earlier intermediate concepts and the more advanced applications introduced in the final year. When the page marks an answer as incorrect, the next step should be to identify the mistaken idea and verify it, rather than memorising the displayed answer letter.

A practical revision routine

Use mixed recall and application questions, then revisit the chapters where formulas, processes or closely related terms are confused. Before attempting the MCQs, review definitions, symbols, unit conversions, graph shapes, diagram labels and the meaning of each term in a formula. Complete a manageable set without notes, check the result, and divide errors into missing knowledge, misunderstood concepts and careless reading. Revise the appropriate section before repeating the chapter.

How to review Atomic Spectra after the quiz

List the questions you missed from Atomic Spectra and write the textbook heading connected with each one. Explain the correct idea in your own words, then return later and answer a fresh set. This gives the chapter page a clear purpose: finding specific weaknesses in Physics rather than only collecting a score.

Accuracy and responsible use

Explanations are provided where they exist in the question bank, but educational databases can contain incomplete or mistaken material. Confirm disputed answers with an authoritative textbook or teacher. Ahmad Learning Hub provides a practice resource and does not claim that a question will appear in an examination or that every available item represents an official board question.