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

Asystematic approach to problem solving is called a (an)

Assume you measured the mass of the cart to be (500 ± 1) g and the mass of the additional mass you put on the cart to be (500 ± 1) g as well. since the scale you are using in the lab cannot measure objects heavier than 600g you will have to sum up individual pieces and propagate the error. so what would be the mass and the standard error of the cart and the mass

On a geologic map, if the contacts between sedimentary rock units form a bull’s-eye pattern of concentric circles, with the youngest unit in the center, the underlying structure is a(n)