What do the four elements most abundant in life - carbon, oxygen, hydrogen and n
ID: 48285 • Letter: W
Question
What do the four elements most abundant in life - carbon, oxygen, hydrogen and nitrogen - have in common?
They all have the same number of valence electrons.
They all have unpaired electrons in their valence shells.
They are elements produced only in living cells.
Each element exists in only one isotopic form.
Question 2
Select one answer.
10 points
What is the correct molecular formula for caffeine (shown here)?
C3H9N4O2
C8H10N4O2
C3H10N4O2
C8H9N4O2
Question 3
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10 points
The lines on the above drawing of caffeine indicate:
Covalent bonds
Hydrogen bonds
Ionic bonds
Polar bonds
Question 4
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10 points
What determines the number of covalent bonds formed by an atom?
Orbitals found in the atom
Electrons in each orbital of the atom
Valence shells in the atom
Electrons in the outer valence shell of the atom
Question 5
Select one answer.
10 points
What do atoms form when they share electron pairs?
elements
molecules
isotopes
Question 6
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10 points
A double covalent bond is the sharing of a total of how many electrons?
2
4
6
8
Question 7
Select one answer.
10 points
Table salt is composed of Na+ and Cl- to form NaCl. This type of bond is called: _____________.
Ionic
Covalent
Polar
Hydrogen
Question 8
Select one answer.
10 points
Will a polar covalent bond form between the two nitrogen atoms in nitrogen gas (N2)?
No because hydrogen is needed to form polar covalent bonds.
Yes, because nitrogen is very electronegative.
Yes, because nitrogen is not very electronegative.
No because both atoms are equally electronegative.
Question 9
Select one answer.
10 points
Weak chemical bonds that form BETWEEN polar molecules are
Covalent bonds
Hydrogen bonds
Ionic bonds
None of these answers are correct.
Question 10
Select one answer.
10 points
Will O2 form a polar covalent bond?
Yes, because oxygen is very electronegative.
Yes, because oxygen is not very electronegative.
No because hydrogen is needed to form polar covalent bonds
No, because both atoms are equally electronegative.
Explanation / Answer
answer 1:- they all have unpaired electrons in valence shell which they use to form covalent bonds
answer 2:-C8H10N4O2
answer 3:-covalent bonds
answer 4:-Electrons in the outer valence shell of the atom, they pair to form inert gas
answer 5:-molecules for example carbon and stom oxygen form carbon die oxide
answer 6:- 4 is the answer
answer 7:- ionic bond, transfer of electron takes place and form NaCl
answer 8:- no because of same electronegativity
answer 9:- hydrogen bonds, because hydrogen bonding are having weak electronegativity
answer 10:- no because both have same electronegativity
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