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Q.54) Among the following. choose the ones with an equal number of atoms,
A. 212 g of $\mathrm{Na}_2 \mathrm{CO}_3$ (s) fuplar mass $=106$ g]
B. 248 g of $\mathrm{Na}_2 \mathrm{O}(\mathrm{s})$ [molar mass $\left.=62 \mathrm{~g}\right]$
C. 240 g of NaOH (s) \{molar mass $=40 \mathrm{gl}$
D. 12 g of $\mathrm{H}_2(\mathrm{~g})$ [molarmass =2 g ]
E. 220 g of $\mathrm{CO}_2(8)$ (molar mass $=44$ ]

Choose the correct answer from the options given below

A)  B, D, anal E only

B) A, B, and C only

C) A, B, and D only

D) B, C, and D only

 

Answers (1)

best_answer

Q.54) We need to calculate the total number of atoms in each option

so the formula 

Total atoms=Number of moles×(Atoms per molecule)×NA

A. 212 g of Na?CO? (Molar mass = 106 g/mol)

  • Moles = 212106=2\frac{212}{106} = 2106212?=2

  • Atoms per unit = 2 Na + 1 C + 3 O = 6 atoms

  • Total atoms = 2 × 6 = 12 atoms

B. 248 g of Na?O (Molar mass = 62 g/mol)

  • Moles = 24862=4\frac{248}{62} = 462248?=4

  • Atoms per unit = 2 Na + 1 O = 3 atoms

  • Total atoms = 4 × 3 = 12 atoms

C. 240 g of NaOH (Molar mass = 40 g/mol)

  • Moles = 24040=6\frac{240}{40} = 640240?=6

  • Atoms per unit = 1 Na + 1 O + 1 H = 3 atoms

  • Total atoms = 6 × 3 = 18 atoms

D. 12 g of H? (Molar mass = 2 g/mol)

  • Moles = 122=6\frac{12}{2} = 6212?=6

  • Atoms per unit = 2 (H? molecule)

  • Total atoms = 6 × 2 = 12 atoms

E. 220 g of CO? (Molar mass = 44 g/mol)

  • Moles = 22044=5\frac{220}{44} = 544220?=5

  • Atoms per unit = 1 C + 2 O = 3 atoms

  • Total atoms = 5 × 3 = 15 atoms

Hence the correct option is (3) A, B, and D only

Posted by

Saumya Singh

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