Atomic Structure, Multiple Choice Questions
Choose the correct answer.
(i) The e/m ratio of cathode ray is ———- C/kg.
| (a) 1.76 × 1023 | (b)1.76 × 1011 | (c) 1.76 × 10-31 | (d) 1.76 × 107 |
Correct Option (b)
| (a) Millikan | (b) J.J Thomson | (c) Chadwick | (d) Moseley |
| (a) Chadwick | (b)Goldstein | (c)J.J Thomson | (d)de Broglie |
| (a)hν | (b) nh/2π | (c) 2hν | (d) 1/2 × hν |
Note: ν is the frequency of radiation.
(v) What will be the wave number of a radiation with λ = 2 × 108 nm?
| (a) 0.5 × 10-8 nm | (b) 10 nm | (c) 5 nm | (d) 100 nm |
Correct Option: (a)
Solution: Wave number = 1/λ = 1/(2×108 nm) = 1/2 × 10-8 nm = 0.5 × 10-8 nm
(vi) Which of the following is not electromagnetic in nature?
| (a) IR rays | (b) X-rays | (c) γ rays | (d) cathode rays |
Correct Option: (d)
Explanation: All electromagnetic radiations are in the range of frequencies of about 3 × 1026 Hz to 3 × 103 Hz. They are further divided into 7 regions containing γ-rays, X-rays, ul (ultra violet) rays, visible light, IR (infra-red), microwaves and radio waves. Cathode rays does not include them.
(vii) Frequency of a green light is 6 × 1014 Hz. Its wave length is ———
a) 500 nm | b) 5 nm | c) 5000 nm | d) 100 nm |
Solution
c=fλ ⇒ λ = c/f ⇒ λ = (3×108)/(6×1014) ⇒ λ = 0.5×10-6 ⇒ λ = 500 × 10-9 m = 500 nm
(viii) If the mass of electron is reduced to half, the Rydberg’s constant …..
| (a) becomes half | (b) becomes double | (c) remains unchanged | (d) becomes one fourth |
Correct Option: (a)
(ix) Which of the following is the mathematical form of Moseley’s law:
| (a) √ν = b(z – a) | (b) √ν = a(z – b) | (c) √ν = a/b √z | (d) √ν = b/z.z |
Correct Option: (b)
(x) For which of the following species, Bohr’s theory does not apply?
| (a) H | (b) H+ | (c) He+ | (d) Li++ |
Correct Option: (b)
(xi) Which of the following set of four quantum numbers is correct for an electron in K-shell?
| (a) n =1, ℓ = 0, m =0, s = +1/2 | (b) n = 2, ℓ = 1, m = 0, s = +1/2 | (c) n = 1, ℓ = 1, m = 0, s = -1/2 | (d) n = 2, ℓ = 2, m = +2, s = +1/2 |
Correct Option: (a)
(xii) The splitting of spectral line in the presence of magnetic field is called …..
| (a) Stark effect | (b) Zeeman effect | (c) Uncertainty Principle | (d) Hund’s rule |
Correct Option; (b)
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