Which one of the following electrons in the ground state will have least amount of energy?
1. | An electron in hydrogen atom. |
2. | An electron in 2p orbital of carbon atom. |
3. | The electron of copper atom present in 4s orbital. |
4. | The outermost electron in sodium atom. |
A monochromatic infrared range finder of power 1milli watt emits photons with wavelength 1000 nm in 0.1 second. The number of photons emitted in 0.1 second is:
(Given: h = \(6.626 \times 10^{-34} J~s\) , c = \(3 \times 10^8 m~s^{-1}, \) Avogadro number = \(6.022 \times 10^{23}\))
1. \(30 \times 10^{37}\)
2. \(5 \times 10^{14} \)
3. \(30 \times 10^{34} \)
4. \(5 \times 10^{11} \)
A ball weighing 10 g is moving with a velocity of 90 ms–1. If the uncertainty in its velocity is 5 %, then the uncertainty in its position is X × 10–33 m. The value of X will be :
[Given : h = 6.63 × 10–34 Js]
1. 1.17
2. 1.37
3. 1.67
4. 1.97
The energy and the radius of the first orbit of He+ are respectively :
1. \(-8.72\times 10^{-18}J\); 0.02645 nm
2. \(8.72\times 10^{-18}J\); 0.02645 nm
3. \(-7.82\times 10^{-18}J\) ; 0.03655 nm
4. \(7.82\times 10^{-18}J\); 0.03655 nm
When electromagnetic radiation of wavelength 300 nm falls on the surface of sodium, electrons are emitted with a kinetic energy of 1.68 ×105 J mol–1. The minimum energy needed to remove an electron from sodium and the maximum wavelength that will cause a photoelectron to be emitted are, respectively:
1. 2.31 × 105 J mol–1, 517 nm
2. 23.1 × 105 J mol–1, 517 nm
3. 3.31 × 105 J mol–1, 417 nm
4. 33.1 × 105 J mol–1, 417 nm
The number of electrons, protons and neutrons in a species are equal to 18, 16 and 16 respectively. The proper symbol of the species is :
1. | \(_{16}^{32}S^{2-}\) | 2. | \(_{18}^{32}S^{2-}\) |
3. | 4. |
The radius of a hydrogen shell is 0.53Å. In its first excited state, radius of the shell will be:
1. 2.12 Å
2. 1.06 Å
3. 8.5 Å
4. 4.24 Å