Which of the statements is NOT true?

1. Correct: Dichromate (${\text{Cr}}_2{\text{O}}_7^{2-}$, orange) converts to chromate (${\text{CrO}}_4^{2-}$, yellow) in alkaline medium ($\text{pH}>7$).2. Correct: Acidified dichromate oxidizes ${\text{H}}_2\text{S}$ to colloidal Sulphur, which gives a milky appearance.3. Incorrect: ${\text{Na}}_2{\text{Cr}}_2{\text{O}}_7$ is hygroscopic (absorbs moisture from air), making it difficult to weigh accurately for standard solutions. ${\text{K}}_2{\text{Cr}}_2{\text{O}}_7$ is preferred in volumetric analysis because it is not hygroscopic and is a primary standard.4. Correct: Standard color of dichromate in acid.