Mass number
Mass number is an concept from the MPSC syllabus, tested in 3 past MPSC questions (2016, 2024, 2025). Below are those real questions with their correct answers and explanations, plus the concepts worth being comfortable with first.
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कार्बनचा अणुक्रमांक किती आहे ? What is the atomic number of carbon ?
Carbon is a chemical element with the symbol C and atomic number 6, meaning it has 6 protons in its nucleus.
पुढील दोन विधानांपैकी कोणते अयोग्य आहे ? अ. अणु अंक म्हणजे अणु केंद्रातील एकूण प्रोटॉन्सची संख्या. ब. अणु वस्तुमान म्हणजे अणु केंद्रातील एकूण प्रोटॉन्स व न्यूट्रॉन्सची संख्या. Which one of the following statements is/are incorrect ? a. The number of protons in a nucleus is called its atomic number. b. The total number of protons and neutrons constitute its mass number.
(a)अणु अंक म्हणजे अणु केंद्रातील एकूण प्रोटॉन्सची संख्या. / The number of protons in a nucleus is called its atomic number.
(b)अणु वस्तुमान म्हणजे अणु केंद्रातील एकूण प्रोटॉन्स व न्यूट्रॉन्सची संख्या. / The total number of protons and neutrons constitute its mass number.
Atomic number is indeed defined as the number of protons in the nucleus, and mass number is the sum of protons and neutrons. Both statements are correct, meaning none is incorrect.
खालीलपैकी कोणते वाक्य चुकीचे आहे ? / Which of the following sentence is wrong ?
(a)अणुकेंद्र हे प्रोटॉन व न्यूट्रॉनने बनलेले असते. / Atomic nucleus is made up of protons and neutrons.
(b)प्रोटॉनवर धनभार असतो. / Proton has a positive charge.
(c)इलेक्ट्रॉनवर ऋणभार असतो. / Electron has a negative charge.
(d)न्यूट्रॉनवर धनभार असतो. / Neutron has a positive charge.
Neutrons are neutral subatomic particles with no electrical charge, so statement (IV) claiming neutrons have a positive charge is factually incorrect.