Which of the following is a fundamental SI unit? | General Science MCQ | Examoogle

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Which of the following is a fundamental SI unit?

Newton

Joule

Mole

Watt

Correct Answer

🔬 SC • Science Concept & PrincipleGeneral ScienceScience

Option C

Mole

Quick Summary:

The International System of Units (SI) defines seven base units from which all other derived units are generated. The mole is the SI base unit for the amount of substance, representing exactly $6.022 imes 10^{23}$ elementary entities.

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🔬SCScience SolutionConcept & Principle

💡 Explanation

💡 Everyday Analogy (Real-World Intuition)

Think of base units as the 'alphabet' of physics and derived units as the 'words' formed by combining those letters; you can form many words, but you start with the fixed set of letters.

🧠 Memory Mnemonic / Shortcut Aid

7 SI Base Units: 'MELTS-AK' (Mass, Electric Current, Luminous Intensity, Temperature, Substance Amount, Amount of time, Kelvin/Length/Kilogram/etc.)

🔢 Key Formulas

$n = \frac{m}{M}$ — calculation of moles where $n$ is moles, $m$ is mass, and $M$ is molar mass

$N = n imes N_A$ — relation to Avogadro's number $N_A$

⚙️ Working Principle

Fundamental units are defined by universal physical constants. The mole is defined by fixing the numerical value of the Avogadro constant, $N_A$ , to be $6.02214076 imes 10^{23} \text{ mol}^{-1}$ . Unlike derived units, which are combinations of base units (e.g., $1 \text{ Newton} = 1 \text{ kg} \cdot \text{m/s}^2$ ), base units are defined independently.

📌 Key Points

▸
There are exactly 7 SI base units: meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol), and candela (cd).
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Derived units like Newton, Joule, and Watt rely on these seven base units.
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The mole bridges the gap between atomic-scale measurements and macroscopic laboratory quantities.

✅ Advantages

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Provides a consistent global standard for scientific communication
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Ensures reproducibility of experimental data across international borders

🛠️ Applications / Uses

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Chemical stoichiometry in pharmaceutical manufacturing
▸
Determining concentrations in analytical chemistry solutions

📄 Additional Information

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Newton is derived: $1 \text{ N} = 1 \text{ kg} \cdot \text{m/s}^2$
▸
Joule is derived: $1 \text{ J} = 1 \text{ kg} \cdot \text{m}^2\text{/s}^2$
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Watt is derived: $1 \text{ W} = 1 \text{ kg} \cdot \text{m}^2\text{/s}^3$

📊 Diagram / Illustration

✅

C is correct — Mole is one of the seven fundamental SI base units, while Newton, Joule, and Watt are derived units.

Core Concepts Used

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SI Base Units Derived Units Avogadro Constant

💡 EXAM TIP

In exams, always look for the 'Big 7'. If the unit can be expressed as a product or quotient of other units, it is definitely a derived unit, not a fundamental one.

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