Answer:
A decrease in [H3O+] and an increase in pH (option a)
Explanation:
Equilibrium of water is shown in this equation
2H₂O ⇄ H₃O⁺ + OH⁻
When you add NaOH, you are modifying [OH⁻]
NaOH → Na⁺ + OH⁻
In equilibrium of water, the [OH⁻] increases
2H₂O ⇄ ↓ H₃O⁺ + OH⁻ ↑
As the [OH⁻] increases, by Le Chatellier, the equilibrium tends to decrease [H₃O⁺].
If the [OH⁻] is higher, pH is also high so the solution of water and sodium hydroxide would be totally basic.
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Hope this helps.
