Why are the symbols ⁷⁹₃₅Br,  and ⁷⁹Br are considered acceptable, whereas  ³⁵₇₉Br and ³⁵Brand  are not acceptable representations of bromine?

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:$\mathrm{}$

What is the number of zinc atoms present in a linear arrangement of length 1.6 cm, given that the diameter of a zinc atom is 2.6 Å?

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