Question

The radius of the first Bohr orbit of hydrogen atom is $0.529\overset{\text{o}}{\mathop{\text{A}}}\,$ . The radius of the third orbit of ${{He}^{+}}$ will be

• A. $8.46\overset{\text{o}}{\mathop{\text{A}}}\,$
• B. $0.705\overset{\text{o}}{\mathop{\text{A}}}\,$
• C. $1.59\overset{\text{o}}{\mathop{\text{A}}}\,$
• D. $4.29\overset{\text{o}}{\mathop{\text{A}}}\,$

Answer 1

Answer: (D)

$4.29\overset{\text{o}}{\mathop{\text{A}}}\,$

Answer 2

According to Bohr model, radius of hydrogen atom $({{r}_{n}})=\frac{0.529\times {{n}^{2}}}{Z}??$ where n = number of orbit Z = atomic number ${{r}_{3}}=\frac{0.529\times {{(3)}^{2}}}{1}$ $=4.761??$