PLEASE HELP ME ASAP question: which of the following represents a polar covalent compound?

choices: a. O2 b. NaCl c. Cl2 d. H2O

all i know is that it isn’t b. NaCl if that helps

Choose each of the settings that follow and list them below do it ill mark brainliest first object= position= speed= acceleration= second object= position= speed= acceleration=

Which of the following is the phase that results when the moon is on the opposite side of the earth from the sun? a. quarter moon b. crescent moon c. new moon d. full moon

Two loudspeakers, 5.5 m apart and facing each other, play identical sounds of the same frequency. you stand halfway between them, where there is a maximum of sound intensity. moving from this point toward one of the speakers, you encounter a minimum of sound intensity when you have moved 0.33 m . assume the speed of sound is 340 m/s. part a) what is the frequency of the sound? part b) if the frequency is then increased while you remain 0.21 m from the center, what is the first frequency for which that location will be a maximum of sound intensity? express your answer to two significant figures and include the appropriate units.