Question

If radius of 2nd stationary orbit is r then the radius of 3rd orbit is

Answer 1

Answer:

Radius is given by formula

rn=0.53×10−10×n2Ao

For 2nd orbit n=2,

r2=0.53×10−10×22Ao=R

For 3rd orbit n=3

r3=0.53×10−10×32Ao

⇒r2r3=49

⇒r3=r2×94=2.25R

Answer 2

Answer:

Explanation:

Radius of 3rd stationary orbit will be 9R/4.

● Explanation -

Let Rb be the Bohr radius.

For an element of atomic number Z, radius of nth Bohr orbit is given by -

Rn = Rb × n^2 / Z

For 2nd orbit,

R2 = Rb × 2^2 / Z

R2 = 4Rb/Z

∴ R2/4 = Rb/Z ...(1)

For third orbit,

R3 = Rb × 3^3 / Z

R3 = 9Rb/Z

∴ R3/9 = Rb/Z ...(2)

Equating (1) & (2),

R2/4 = R3/9

R3 = (9/4) R2

Also, R2 = R,

∴ R3 = 9R/4

Hence, radius of 3rd stationary orbit will be 9R/4.

Hope this helps you.

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