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 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

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

The number of protons, neutrons and electrons in  \( _{71}^{175}Lu\) respectively, are:

1. 104, 71 and 71

2. 71, 71 and 104

3. 175, 104 and 71

4. 71, 104 and 71