Geo-Scientist Prelims 2026 Chemistry Q38: Despite of being obtained in high purity, sodium thiosulphate is…

Despite of being obtained in high purity, sodium thiosulphate is unsuitable as a primary standard. This is because :

1. CO₂ present in ordinary distilled water may decompose it
2. It can be decomposed by bacterial action
3. It decomposes upon exposure to light

Select the correct answer using the code given below :

1. (a) 1 and 2 only
2. (b) 1 and 3 only
3. (c) 2 and 3 only
4. (d) 1, 2 and 3