Explanation:
The 2019 water crisis in Chennai has made us realize the importance of saving water more than ever. Water, as we all know, is a finite resource without which our planet would be a barren wasteland. Today with our increasing population it would be logical to say that our water consumption has also increased. And with increasing demand and lesser supply, water scarcity arises. Our ancestors who had foreseen the potential dangers of water scarcity had developed methods to conserve water that was suited for the varied terrain of the Tamil-speaking kingdoms.
Traditional Rainwater Conservation methods of Tamil Nadu
Eri
There are no perennial rivers in Tamil Nadu except the Thamirabharani River which flows through Thirunelveli district. And so, several hundred years ago a simple system was devised to utilize the rainwater to the fullest. An Eri or tank system is one of the oldest forms of water conservation systems in India. Many Eris are still in use in Tamil Nadu and play an active role in irrigation. They act as water reservoirs and flood control systems. They prevent soil erosion, recharge groundwater, and prevent wastage of runoff water during heavy rainfall.
Kudimaramathu
Kudimaramathu is one of the old traditional practice of stakeholders participating in the maintenance and management of irrigation systems. During earlier days, citizens of a village used to actively participate in maintaining the water bodies of their village by deepening and widening the lakes and ponds and restoring the water bodies back to their original form. The silt, rich in nutrients, collected in the process would be used by the farmers themselves in their field. A sense of collective ownership ensured the continued survival of the water bodies.
Answer:
0.250 moles of MgO are produced when 0.250 mol of Mg reacts completely with O₂
Explanation:
In first place, the balanced reaction between Mg and O₂ is:
2 Mg + O₂ ⇒ 2 MgO
By stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of reactants and products participate in the reaction:
- Mg: 2 moles
- O₂: 1 mole
- MgO: 2 moles
Then you can apply the following rule of three: if by reaction stoichiometry 2 moles of Mg produce 2 moles of MgO, 0.250 moles of Mg, how many moles of MgO will they form?

moles of MgO= 0.250
<u><em>0.250 moles of MgO are produced when 0.250 mol of Mg reacts completely with O₂</em></u>
Turning things to gram so need to convert to the metric system
<span>35 grams
The average salinity of seawater is 35 parts per thousand, so multiply the mass of seawater provided by 0.035 and you'll get the amount of salt (mostly sodium chloride) dissolved in it. So
1000 g * 0.035 = 35 g
Therefore in 1 kilogram of seawater with average salinity, there is 35 grams of salt.</span>