#SIGNIFICANTFIGURES
🌱 Definition
Digits which convey certainty + one uncertain digit

⭐ Rules to Count Significant Figures
✔️ All non-zero digits → significant
✔️ Zeros between non-zero → significant
✔️ Leading zeros → ❌ not significant
✔️ Trailing zeros → significant only with decimal

📌 Examples:
0.0045 → 2 SF
2.300 → 4 SF
1500 → 2 SF (without decimal)

➕➖ Addition / Subtraction
Result → least decimal places
📌 Example:
12.11 + 0.2 = 12.3

✖️➗ Multiplication / Division
Result → least significant figures
📌 Example:
2.5 × 1.23 = 3.1 (2 SF)

🔢 Rounding Off Rules
Next digit < 5 → same
Next digit ≥ 5 → +1
📌 2.34 → 2.3
📌 2.36 → 2.4

#NEETHOTPOINTS
✔️ Exact numbers → infinite SF
✔️ Unit conversion → SF maintained
✔️ Final answer rounding last step

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Question 1 (Concept + Limiting Reagent):

A mixture contains 4 g H₂ and 32 g O₂.
They react according to:
2H2+O2= 2H2O
Find:
(i) Limiting reagent
(ii) Mass of water formed
(iii) Mass of excess reactant left

Question 2 (Gas + Stoichiometry + Trick)

At STP, 11.2 L of a gaseous hydrocarbon reacts completely with excess O₂ to produce 44 g CO₂.
Identify the hydrocarbon.

Question 3 (Equivalent + Redox + Stoichiometry )

A 10 g mixture of Na₂CO₃ and NaHCO₃ is completely neutralised by 200 mL of 1 N HCl.
Find the mass percentage of Na₂CO₃ in the mixture.

#SIGNIFICANTFIGURES

Question :1 Evaluate the result with correct significant figures:
(2.36+0.040) +1.2

Question 2
The mass of a cube is measured as 2.50 g and each edge is measured as 1.20 cm.
Calculate the density of the cube with correct significant figures.



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