Volume of 3 M NaOH (formula weight 40 g mol⁻¹) which can be prepared from 84 g of NaOH is _____

Volume of 3M NaOH Solution | JEE Mains PYQ | Mole Concept

Q. Volume of 3 M NaOH (formula weight 40 g mol⁻¹) which can be prepared from 84 g of NaOH is ______ × 10⁻¹ dm³.

Explanation

Step 1: Calculate number of moles of NaOH

Given mass of NaOH = 84 g
Molar mass of NaOH = 40 g mol⁻¹
Moles of NaOH = 84 ÷ 40 = 2.1 mol

Step 2: Use molarity formula

Molarity (M) = Number of moles / Volume (in dm³)

Step 3: Calculate volume of solution

Volume = Moles / Molarity
Volume = 2.1 ÷ 3 = 0.7 dm³

Step 4: Express volume in required form

0.7 dm³ = 7 × 10⁻¹ dm³

Correct Answer = 7

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