Which of the following best describes a covalent bond?

Achemist who studies water samples did a demonstration of how to test for lead in water. she added a clear solution of potassium iodide to a clear solution of lead nitrate. then a yellow swirling solid formed in the liquid. what is most likely true about the yellow solid?

20 grams of water. she poured out 15 grams. which of the following physical properties of the water changes? a .boiling point b. density c .electrical conductivity d .volume

How many moles of na2s2o3 are needed to react with 0.12mol of cl2? show work.