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

Which of the following gives the atomic numbers of the elements having outermost electronic configurations 3s¹ and 2p⁵, respectively?

Calculate the number of electrons corresponding to a charge of 2.5 × 10⁻¹⁶ C.

How many carbon atoms of diameter 0.15 nm can be placed side by side to form a straight line of length 20 cm?$\mathrm{}$

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?

Find the radius of each carbon atom if 2 × 10⁸ identical carbon atoms arranged side by side form a straight line of length 2.4 cm.

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 wavelength of yellow light emitted by a sodium lamp is 580 nm. Calculate its frequency and wave number, 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

Calculate the wave number of light having a time period of 2.0 × 10⁻¹⁰ s. 

1. 16.66 m^–1

2. 1.66 m^–1

3. 32.34 m^–1

4. 12.34 m^–1

In Rutherford's \(\alpha\)-particle scattering experiment, a thin foil of heavy metals like gold or platinum is typically used. If a lighter metal foil, such as aluminum, were used instead, how would the observed deflection patterns change?

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

Which of the following statements about the properties of X-rays is incorrect?

1.  X-rays can ionize gases.

2.  X-rays produce fluorescence in zinc sulphide (ZnS).

3.  X-rays are deflected by electric and magnetic fields.

4.  X-rays have shorter wavelengths than ultraviolet rays.