Q1.
Mixtures could be of several types depending on the physical state of their components. Some mixtures with their examples are shown in Table 8.1. Complete the third column—
Answer
The column to be filled is the one headed Uniform or non-uniform. Judge each example by one test: can the components be seen separately?
| S.No. | Mixture-type | Examples | Uniform or non-uniform |
|---|---|---|---|
| 1. | Gas and gas | Air | Uniform |
| 2. | Gas and liquid | Aerated water (soda water) Oxygen dissolved in water | Uniform Uniform |
| 3. | Solid and gas | Carbon particles in air | Non-uniform |
| 4. | Liquid and liquid | Acetic acid in water (vinegar) Oil and water | Uniform Non-uniform |
| 5. | Solid and liquid | Sand and water Seawater | Non-uniform Uniform |
| 6. | Solid and solid | Baking powder (baking soda and tartaric acid) Alloys | Non-uniform Uniform |
Why these answers: Soda water, dissolved oxygen, vinegar and seawater are all cases where one substance has dissolved fully in the other, so the mixture is the same everywhere — uniform. Carbon particles in air, oil on water and sand in water stay as separate specks, layers or grains you can see, so they are non-uniform. Baking powder is a mechanical mixture of two white powders — under a magnifying glass the two kinds of grains can be told apart. Alloys are the special case: metals melted together mix so evenly that even a microscope shows one substance throughout.
Tip: The English book says "Complete the third column" while the blank column in Table 8.1 is actually the fourth; the Hindi edition of the same page correctly says चौथा स्तंभ (fourth column). Fill the Uniform or non-uniform column.