The total number of electrons present in one mole of methane is:
The total number and mass of neutrons in 7 mg of 14C would be :
(Assume that mass of a neutron = 1.675 × 10–27 kg)
\(1 .\) \(2 . 41\) \(\times\) \(\left(10\right)^{21}\) \(,\) \(4 . 03\) \(\times\) \(\left(10\right)^{– 6}\) \(kg\)
\(2 .\) \(6 . 23\) \(\times\) \(\left(10\right)^{23}\) \(,\) \(1 . 67\) \(\times\) \(\left(10\right)^{- 21} kg\)
\(3 .\) \(1 . 22\) \(\times\) \(\left(10\right)^{22}\) \(,\) \(4 . 03\) \(\times\) \(\left(10\right)^{6}\) \(kg\)
\(4 . 2 . 41\) \(\times\) \(\left(10\right)^{21}\) \(,\) \(4 . 03\) \(\times\) \(\left(10\right)^{- 6}\) \(g\)
The wave number of a light whose time period is 2.0 × 10–10 s would be:
1. 16.66 m-1
2. 1.66 m-1
3. 32.34 m-1
4. 12.34 m-1
The number of photons of light with a wavelength of 4000 pm that provide 1J of energy would be:
Electromagnetic radiation of wavelength 242 nm is just sufficient to ionise sodium atom. The ionisation energy of sodium in kJ mol-1 is -
1. 494
2. 4.94
3. 516
4. 0.50
A 25-watt bulb emits monochromatic yellow light with a wave length of 0.57µm. The rate of emission of quanta per second would be :
1. 7.17×10-19 s-1
2. 4.13×1016s-1
3 . 7.17×1019 s-1
4 . 1.26 ×1020s-1
The wavelength of light emitted when the electron in a H atom undergoes the transition from an energy level with n = 4 to an energy level with n = 2, is :
1. 586 mm
2. 486 nm
3. 523 nm
4. 416 pm
The energy associated with the fifth orbit of a hydrogen atom is :
The wave number for the longest wavelength transition in the Balmer series of atomic hydrogen would be -
1. \(1 . 1 . 52 \times \left(10\right)^{6} m^{- 1}\)
2. \(2 . 3 . 14 \times \left(10\right)^{6} \left(cm\right)^{- 1}\)
3. \(3 . 15 . 2 \times \left(10\right)^{6} m^{- 1}\)
4. \(4 . 1 . 52 \times \left(10\right)^{6} \left(cm\right)^{- 1}\)
The energy of an electron in an H - atom is given by \(E_n=(-2.18 \times10^{-18})/n^2~\mathrm J.\) The shortest wavelength of light that can be used to remove an electron completely from \(n = 2\) orbit will be:
1. | \(3647~\mathring{\mathrm A}\) | 2. | \(5132~\mathring{\mathrm A}\) |
3. | \(3017~\mathring{\mathrm A}\) | 4. | None of these |