The answer is the 1st statement.
The stability of atoms depends on whether or not their outer-most shell is filled with electrons. If the outer shell is filled, the atom is stable. Atoms with unfilled outer shells are unstable, and will usually form chemical bonds with other atoms to achieve stability.
D) Contour plowing is used to reduce erosion and sediment pollution.
Explanation:
Contour plowing in farming helps to prevent pollution by reducing surface erosion of topsoil and preventing sediment pollution.
Contour plowing is a farming technique in which crops are planted along the slopes of hills or contoured areas.
- The rate at which rain water and precipitation moves along slope terrain is very fast.
- This causes the washing off of the the topsoil on hills to eroded very fast.
- Contour plowing breaks the slope and farming is done along movement on the contour.
- This prevents topsoil erosion.
- It also prevents sediment pollution in nearby streams and water bodies that are located around the valley at the base of the hill.
Learn more:
Soil erosion brainly.com/question/2473244
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Answer:
What are so called breast-cancer genes, are mutations in two genes: BRCA1 (BReast CAncer gene one) and BRCA2 (BReast CAncer gene two), and are also associated with ovaric cancer. According to the question, these genes are present in the popolation despite surgeries and deaths, and asks why. Surgeries does not eliminate the genes, they eliminate the tumors, and people can still reproduce after that. And also, most people already had offspring before they know they have cancer, so they are inheriting the mutations on the genes anyway.
Explanation:
