Symbols ${}_{35}{}^{79}\mathrm{Br}$ and ${}^{79}Br$ can be written,
whereas symbols ${}_{79}{}^{35}\mathrm{Br}$ and ${}^{35}Br$ are not acceptable because:

The atomic number of elements whose outermost electronic configuration are represented by 3s¹ and 2p⁵ respectively, is:

A certain particle carries 2.5 × 10^–16 C of static electric charge. The number of electrons present in it would be:

If the diameter of a carbon atom is 0.15 nm, the number of carbon atoms that can be placed side by side in a straight line across the length of the scale of length 20 cm long will be:$\mathrm{}$

The diameter of a zinc atom is 2.6 Å. If zinc atoms are arranged side by side lengthwise, number of atoms present in a length of 1.6 cm would be:
1. 5.153 × 10⁷
2. 6.153 × 10⁷
3. 4.153 × 10⁹
4. 6.153 × 10³

2 × 10⁸ atoms of carbon are arranged side by side. The radius of a carbon atom if the length of this arrangement is 2.4 cm would be :

1. 7.0 × 10^–11 m

2. 5.0 × 10^–11 m

3. 8.0 × 10^–11 m

4. 6.0 × 10^–11 m

Yellow light emitted from a sodium lamp has a wavelength (λ) of 580 nm. The frequency (ν) and wave number of this yellow light would be, respectively:

1. 517 × 10¹⁴ s^–1 , 172 × 10⁶ m^–1

2. 6.17 × 10¹⁴ s^–1 , 1.72 × 10⁶ m^–1

3. 4.17 × 10¹⁴ s^–1 , 2.72 × 10⁶ m^–1

4. 5.17 × 10¹⁴ s^–1 , 1.72 × 10⁶ m^–1

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

In Rutherford's experiment, generally, the thin foil of heavy atoms like gold, platinum, etc. have been used to be bombarded by the α-particles.

 If the thin foil of light atoms like aluminum etc. is used in Rutherford’s experiment, the difference that would be observed from the above results is :

1. The same results will be observed.

2. More deflection would be observed.

3. There will not be enough deflection.

4. None of the above.

The incorrect statement regarding the characteristics of X-rays is :

1. The radiation can ionize the gas

2. It causes a fluorescence effect on ZnS

3. It is deflected by electric and magnetic fields

4. Have a shorter wavelength than ultraviolet rays