Answer:
Oxygen
Explanation:
The electrons present in an atom are arranged in shells or orbitals. The electrons are filled into these shells based on their energy levels with those shells closest to the nucleus filled first as they have the lowest energies.
The arrangement of electrons around the nucleus of an atom is known as electronic configuration. The outermost electron shell of an atom is known as a valence shell shell and the electrons found in this shell are known as valence electrons. The electrons usually exist in pairs. The first shell can only contain two electrons; the second shell can contain 8. the electrons are singly filled first before pairing occurs.
The electronic configuration of the atoms of the elements in the option are as follows:
Helium : 1s² ; valence electrons are 2 which are both paired
Hydrogen: 1s¹ ; valence electron is 1
Oxygen : 1s²2s²2p⁴ ; valence electrons are 6 wit two unpaired electrons
Lithium : 1s²2s¹ ; valence electron is 1
Helium has two valence electrons but they are paired as its 1s shell can only contain a maximum of two electrons.
Oxygen has 6 valence electrons. Two of these electrons are paired while the other two are unpaired.
A.
preventing fish from moving along a river.
B.
serving as a place for people to have picnics.
C.
increasing fresh water sources for humans.
D.
providing new wildlife habitats.
Answer:
A. Preventing fish from moving along a river.
Explanation:
1. Dams create barriers and trap the water that builds up behind it. This prevents fish from moving along the river as there's a barrier in place and is just overall harder for the fish to move freely along a river because of it.
2. It's the only negative option as the others are all positive outcomes, while the question asks for a negative outcome instead.
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Answer:
subsoil or horizon b I hope it will help you please follow me
The statement that correctly describes the presence of freckles is there are two alleles for freckles, hence option B is correct.
An allele is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution.
Small, brownish to reddish dots on your skin are known as freckles. They frequently appear on your face, neck, back, upper chest, hands, and arms, as well as other sun-exposed places. Even though freckles are typically not harmful, it is always a good idea to keep an eye out for any changes.
Therefore, the statement that correctly describes the presence of freckles is there are two alleles for freckles, hence option B is correct.
Learn more about alleles, here:
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Answer:
b
Explanation:
edge2020
A. non-renewable
B. valuable
C. renewable
Answer:
B. valuable
Explanation:
non renewable: oil
renewable: wind
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Answer:
The phase that not all cells enter, but is a phase where cells are not actively dividing is called the G0 or non-dividing phase.
Answer:
G₀ phase
Explanation:
Some types of cells divided slowly or not at all. These cells may exit the G₁ phase and enter a resting phase called G₀ phase. In G₀ phase, a cell is not actively preparing to divide. It's simply doing its job. For some cells, G₀ is a permanent state, while others may restart cell division given the right signals.
contracts to move substances through the body
B.
provides structure and support
C.
removes metabolic waste products from the body
D.
breaks down food to acquire nutrients