The chemical equation below is unbalanced. Zn + HCl ---> ZnCl2 + H2

Which is the correct balanced chemical equation?

Group of answer choices

Zn + HCl ---> ZnCl + H

Zn + H2Cl2 ---> ZnCl2 + H2

Zn + 2HCl ---> ZnCl2 + H2

2Zn + 2HCl ---> ZnCl2 + H2

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.

In the following table, all the columns for the element calcium are filled out correctly. element electron structure of atom electron structure of ion net ionic charge calcium 1s22s22p63s23p64s2 1s32s22p63s23p64s1 +1 true false

Which organism develops breathing organism develops breathing organs from pharyngeal arches? shark, spider, sea star, sea horse