CHEMISTRY HIGH SCHOOL

Which of the following cannot pass across the placenta?(a) oxygen
(b) waste materials
(c) blood
(d) nutrients

Answers

Answer 1
Answer: The placenta is the structure that allows for transfer of wastes, oxygen, and
nutrients between the mother and the fetus.  The fetal blood comes extremely
close to the maternal blood in the placenta, but there is no intermingling of fetal
and maternal blood.  The fetus and mother can even have, and often do have,
different blood types.
Answer 2
Answer: Oxygen cannot pass through the placenta

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How do valence electrons affect reactivity?

Answers

The less valence electrons there are, the less stable the atom becomes, causing it to react with other atoms. More valence electrons adds mass to the atom, making it less reactive

What are the properties of an ionic bond?

Answers

Answer:

Ionic Compounds have high boiling and melting points as they're very strong and require a lot of energy to break. The electrostatic forces of attraction between oppositely charged ions lead to the formation of ions. Ionic compounds form crystals. These compounds are brittle and break into small pieces easily.

Explanation:

How many total valence electrons take part in a triple bond between 2 atoms?

Answers

6, to do a single bond you need two singular valence electrons to create one bond. Therefore to create a triple bond you need 6 singular valance electrons.

When an individual has an energy surplus, he or she stores the extra energy as: A. nucleic acids. B. lipids. C. None of the answer options is correct. D. carbohydrates. E. proteins.

Answers

Answer: B. lipids

Explanation:

When an individual has an energy surplus, the extra energy is stored in the body as lipids. Lipids are used for energy in the long term

Which statement best compares the energy involved in melting with the energy involved in boiling for a given liquid?A....Energy is removed from the particles in each change, but more energy is removed in melting than in boiling because the attractions are weaker.

B....Energy is removed from the particles in each change, but more energy is removed in boiling than in melting because the attractions are weaker.

C....Energy is added to the particles in each change, but boiling requires more energy than melting because the attractions must be completely overcome.

D....Energy is added to the particles in each change, but melting requires more energy than boiling because the attractions must be completely overcome.

Answers

The correct answer is C.  When a solid turns into a liquid the intermolecular forces are just weakens enough to allow the molecules to move around each other.  When a liquid turns into a gas the intermolecular forces need to be completely broken since gases ideally do not have any attraction between its particles.  It takes a lot more energy to completely brake intermolecular attractions than it does to weaken them.  
I hope this helps.  Let me know if anything is unclear.

C. Energy is added to the particles in each change, but boiling requires more energy than melting because the attractions must be completely overcome.

Which of these elements has four total electrons in its outer p orbitals? A) barium (Ba)
B) nitrogen (N)
C) silicon (Si)
D) sulphur (S)

Answers

SulphurS 161s22s22p63s23p4

The element that has four total electrons in its outer P orbitals is

Sulphur (s) (answer D)

Sulphur is in group 16 and period 3 in the periodic table therefore Sulphur is in atomic number 16.

Sulphur (S) electronic configuration is 1S2 2S2 2P6 3S2 3P4 or [Ne] 3S2 3P4 therefore the 3P4 subshell of sulphur has only 4 electrons.
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