a. Which of the following true statements support the conclusion that lead is a chemical element? (Select all that apply)

Group of answer choices

1-Lead changes from face-centered-cubic structure to hexagonal-close-packed structure under high pressure

2-The mineral scrutniyite produces lead and oxygen in a mass ratio of 207 grams of lead to 32 grams of oxygen whereas the mineral litharge produces lead and oxygen in a ratio of 207 grams of lead to 16 grams of oxygen.

3-When naturally occurring bronzes are heated, lead metal melts and flows out after tin and before other components of the bronze melt.

4-No known chemical process breaks lead into other chemical elements

5-Lead has a density of 11,300 kg/m³

b. How many moles of helium atoms are in 7.55 cubic meters of helium gas at a temperature of 298 K and 101,000 Pa of pressure?

c. A rotary lever with a length of 0.59 m rotates 20.when a force of 160 N is applied to it. What is the maximum possibleworkthis lever can do innewton-meters?