Apiece of metal is dropped into a solution of acid. using a sharp probe, the metal is broken into smaller pieces while in the solution. also while in the solution, some of the metal reacts, producing hydrogen gas. which statement is true about the changes that have occurred? a. only physical changes have occurred. b. no physical or chemical changes have occurred. c. only chemical changes have occurred. d. physical and chemical changes have occurred.

At a temperature of 393 k, the temperature of a sample of nitrogen is 1.07 atm what will the pressure be at a temperature of 478 k

Stage in which a star’s outer layers have started to cool and grow outward?

For a research project, a student decided to test the effect of the lead(ii) ion (pb2+) on the ability of salmon eggs to hatch. this ion was obtainable from the water‐soluble salt, lead(ii) nitrate, which the student decided to make by the following reaction. pbo(s) + 2 hno3(aq) → pb(no3)2(aq) + h2o losses of product for various reasons were expected, and a yield of 86.0% was expected. in order to have 5.00 g of product at this yield, how many grams of pbo should be reacted? (assume that sufficient nitric acid, hno3, would be used.)