quiz #2 (biology)

about 25% of the 92 natural elements are known to be essential to life. which four of these 25 elements make up approximately 96 percent of living matter?

• carbon, oxygen, phosphorus, hydrogen

• carbon, sodium, hydrogen, nitrogen

• carbon, hydrogen, nitrogen, oxygen

• oxygen, hydrogen, calcium, nitrogen

which of the following are compounds?

• H20, O2

• h20, O2, CH4

• O2 and CH4

• H20, CH4, but not O2

if you change the number of neutrons in an atom, you create a....

• isotope

• compound

• anion

• cation

which one of the atoms shown would be most likely to form an anion with a charge of -3?

• two on first line, one on top line

• two on first line, five on second line

• two on first line, four on second line

• two on first line, seven on second line

what is the maximum number of covalent bonds that an oxygen atom with atomic number 8 can make?

• none

• 10

• 1

• 2

a covalent chemical bond is one in which...

• outer shell electrons of ONE atom are transferred to fill the inner electron shell of another atom

• electrons are removed from one atom and transferred to another atom so that the two atoms become oppositely charged

• protons and neutrons are shared by two atoms so as to satisfy the requirements of both atoms

• outer shell electrons of TWO atoms are shared so as to satisfactorily fill their respective orbitals

how many electrons are involved in a covalent double bond?

• six

• five

• four

• three

Nitrogen is more electronegative than hydrogen. which of the following is a correct statement about the atoms in ammonia?

• ammonia has an overall NEGATIVE charge

• each hydrogen atom has a PARTIAL positive charge; the nitrogen atom has a PARTIAL negative charge

• ammonia has an overall POSITIVE charge

• the nitrogen atom has a PARTIAL positive charge; each hydrogen atom has a PARTIAL negative charge

if an atom has a charge of -1, which of the following must be true?

• same number of protons than neutrons

• it has two more protons than neutrons

• it has one more electron than it does protons

• same number of protons than electrons

why is carbon so important in biology?

• forms a variety of carbon skeletons and host functional groups

• common element on earth

• very little electronegativity, making it a good electron donor

• it bonds to only a few other elements