How to you distinguish dilute nitric acid and concentrated nitric acid using chemical methods?

I have two methods to distinguish between concentrated and dilute nitric acid

Method 1: Using magnesium/manganese.

Mg + 2HNO₃ (1%) → Mg(NO₃) + H₂

very very dilute

Mg + 4HNO₃ → Mg(NO₃)+ 2H₂O +2NO₂

concentrated

In the first reaction of magnesium with concentrated nitric acid, hydrogen is evolved.

In the second reaction of magnesium with very very dilute nitric acid, water is evolved.

Using the respective tests for hydrogen and water, we can test them.

Method 2: Using iron.

3 Fe + 8HNO₃→ 3Fe(NO₃)₂ + 4H₂O + 2NO

dilute

Fe + 6HNO₃→ Fe(NO₃)₃ + 3H₂O + 3NO₂

   concentrated

In the first case of method 2,

Fe(NO₃)₂ ⇆ Fe²⁺ + (NO₃) ⁻       Iron with valency 2+ is formed

In the second case of method 2,

Fe(NO₃)₃ ⇄ Fe³⁺ + (NO₃) ⁻        Iron with valency 3+ is formed

Brainlist pls!

the answer is d. 74.02