The amount of iron in steel can be determined by titration with dichromate. first, the steel is dissolved in hydrochloric acid to oxidize all the iron to fe 2 + . an indicator is added that will react with excess dichromate. then, potassium dichromate is added to the solution until the end point is reached. cr 2 o 2 − 7 + 6 fe 2 + + 14 h + ⟶ 2 cr 3 + + 6 fe 3 + + 7 h 2 o for the analysis of 2.00 g of steel, the titration required 21.20 ml of 0.1800 m k 2 cr 2 o 7 . what was the mass percentage of iron in this steel sample?

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? a. the balloons both rise. the cold balloon is larger than the warm balloon. b. the balloons rise at the same rate. both balloons are the same size. c. the warm balloon expands and rises. the cold balloon shrinks and sinks. d. the cold balloon expands and rises. the warm balloon shrinks and sinks.

What are the genotypic and phenotypic ratios

Answer asap : ( a. how does mucus prevent the entry of pathogens? b. describe two ways white blood cells protect us from pathogens.