Basic Concepts in Chemistry Flashcards for NEET — 20 cards

First 8 of 20 Basic Concepts in Chemistry flashcards

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1. Card 1 of 20

   State Gay Lussac’s Law of Gaseous Volumes.

   Hint: Volume ratio = Mole ratio (for gases)

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   Answer

   When gases combine or are produced in a chemical reaction, they do so in a simple ratio by volume, provided all gases are at the same temperature and pressure.

2. Card 2 of 20

   What is the definition and value of 1 amu (Atomic Mass Unit) or 1 u (Unified Mass)?

   Hint: Standard reference is C-12 isotope

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   Answer

   1 amu is defined as exactly 1/12th the mass of one Carbon-12 atom. Value: $1.66056 \times 10^{-24} \text{ g}$.

3. Card 3 of 20

   What is the difference between Precision and Accuracy in measurements?

   Hint: Precision = Consistency, Accuracy = Correctness

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   Answer

4. Card 4 of 20

   State the Law of Definite Proportions (Proust's Law).

   Hint: Water from rain or river is always H2O (1:8 by mass)

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   Answer

   A given chemical compound always contains its component elements in fixed ratio (by mass) and does not depend on its source and method of preparation.

5. Card 5 of 20

   Provide the formula for calculating average atomic mass.

   Hint: If abundance is in %, divide by 100

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   Answer

   Average Atomic Mass = $\sum (\text{Fractional Abundance} \times \text{Isotopic Mass})$.

6. Card 6 of 20

   Define the Mole Concept and Avogadro's Number ($N_A$).

   Hint: Chemist's dozen

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   Answer

   One mole is the amount of a substance that contains as many particles (atoms, molecules, ions) as there are atoms in exactly 12g of the Carbon-12 isotope. $N_A = 6.022 \times 10^{23}$.

7. Card 7 of 20

   What is the molar volume of an ideal gas at Standard Temperature and Pressure (STP)?

   Hint: Most NEET numericals still use 22.4 L for 1 atm

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   Answer

   At classical STP ($0^\circ\text{C}$, 1 atm), the molar volume is 22.4 L. At IUPAC STP ($0^\circ\text{C}$, 1 bar), the molar volume is 22.7 L.

8. Card 8 of 20

   What is the formula for Mass Percentage of an element in a compound?

   Hint: Part / Whole * 100

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   Answer

   Mass % of an element = $\left( \frac{\text{Mass of that element in 1 mole of compound}}{\text{Molar mass of compound}} \right) \times 100$