JEE Main Chemistry question

The dissociation of water at 25°C is 1.9×10⁻⁷ percent, the density of water is 1.0 g/cm³. The ionisation constant of water is:

• (A)3.42×10⁻⁶
• (B)3.42×10⁻⁸
• (C)1.00×10⁻¹⁴Correct
• (D)2.00×10⁻¹⁶