Answer: The Relative humidity is 50%
Explanation: Relative humidity is the ratio of the air’s water vapour content (the actual amount of water vapour in the air) to its water vapour capacity at a given temperature. It depends on temperature and the pressure of the system of interest and it is usually expressed in PERCENTAGE; the higher the percentage, the more humid the air/water mixture.
The formula of Relative humidity (%) = (water vapor content / water vapor capacity) x 100%
Where: Water vapour content is the actual amount of water vapour in the air. Which is 10g/cm³ from the question above;
Water vapour capacity is the air's capacity to hold water vapour. Which is 20g/cm³ from the question above.
Therefore, RH(%)= (10g/cm³ / 20g/cm³) x 100 = 0.5 x 100= 50%
This means that the air contains half of the water vapour it could hold at 20 degree Celsius.
In acid soils you can select the crops that can growth in this conditions (pH 6.0 - 6.5 is slightly acidic, and you can find cultures that can be cropped under this conditions). If soil is acid to highly acidic , in some areas of Northern Spain the use to increase the pH by liming the soil in a gradual / gentle way. You can find different product for liming fron rocks, wastes (from marble industries; animal bones; etc
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It is the sun. You start with photosynthesis.