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Atoms and Molecules — Science STD 9 — Question

Gujarat BoardEnglish MediumSTD 9ScienceAtoms and Molecules1 Mark
MCQ
The molecular weight of calcium carbonate CaCO3​ is:
  • A
    80
  • B
    90
  • C
    100
  • D
    110
✓

Answer

  1. 100

Explanation: 

Molecular weight is the mass of whole molecule.

Steps:- (1) Chemical formula of calcium carbonate ⟶CaCO3​

(2) Mass of Calcium⟶ 40

     Mass of Carbon⟶ 12

     Mass of Oxygen⟶ 16

(3) Multiply mass of each element by number of atoms of that element.

(4) Add all the masses obtained after multiplication.

⟶CaCO3​

= 1 × 40 + 1 × 12 + 3 × 16

= 40 + 12 + 48

= 100.

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