Radishes will always grow best with water, however if you dilute milk or soda with water they can be used as well.
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No doubt they will, but the plant is only interested in the water. Soda is nothing more than a solution of sugar, with perhaps flavourings, and carbon-dioxide in water anyway. Don't waste your money - use just water.
A Few Things...
No but fertilizer and lots of water help radishes to grow.
Because it thinks that you will like it better when its liquid.
water
yes they can
Water
No
No other liquid is similar to water.
A pure liquid is a liquid that is not contaminated with any other compound. If water is pure water, then it is a pure liquid. However, shampoo is not a pure liquid.
Water particles mixed with other liquid particles. Example: water and oil or water and cordial.
To varying degrees, yes. Nothing is a better solvent under normal, laboratory/household conditions than water though.
because liquid mixes in food and water to dissolve