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. \(5 \times 10^{11} \)

Which one of the following electrons in the ground state will have least amount of energy?

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. ${}_8{}^{16}\mathrm{S}$

4. ${}_{16}{}^{32}\mathrm{S}$

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