RBSE Guide
Science ·Class 9 Science

Find the formula unit mass of magnesium hydroxide, Mg(OH)2. Class 9

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· Jul 06, 2026 · Reviewed & updated Sep 17, 2026 · 1 min read

Find the formula unit mass of magnesium hydroxide, Mg(OH)2. Class 9


Question 1.

Find the formula unit mass of magnesium hydroxide, Mg(OH)2. Class 9

Atomic mass — Mg = 24 u; 0 = 16 u; H = 1 u.

Answer:

Mg(OH)2 contains: 1 magnesium ion and 2 hydroxide ions.

Mg: 1 atom, O: 2 atoms, H: 2 atoms.

Formula unit mass of Mg(OH)2

= (24 u × 1) + (16 u × 2) + (1 u × 2)

= 24 + 32 + 2 = 58 u