Why might the percent yield of copper produced be less than 100% of the expected amount?

[ ] There are impurities in the substances.
[ ] The reaction might not have gone to completion.
[ ] The amount of one of the reactants might be measured incorrectly.

(you can pick multiple)

What happened in 2012 and how does it illustrate the importance of understanding the sun and how it works?

The reactions of photosynthesis occur in the of plant cell? a.mitochondria. b. lysosomes. c. chloroplasts. d. chlorophyll

Plz me ! 1 which of earths spheres contains most of its mass? a atmosphere b hydrosphere c geosphere* d biosphere 2 erosion and weathering are examples of which types of forces? a constructive forces b destructive forces* c gravitational forces d inertia-related forces 3 which of the following statements about earths atmosphere is true? a earths atmosphere contains 78% water vapor which is essentail to life b earths atmosphere contains 21% oxygen c earths atmosphere contains carbon dioxide which all life forms require d earths atmosphere allows radiation from the sun to pass through it and warm earths surface* 4 the strenght of the force of gravity between two objects is determined by which of the following factors? select all that apply a the messes of the objects* b the distance between the objects* c the volumes of the objects d the surface area of the objects 5 earth and moon are kept in there respective orbits due to the influence of a inertia b gravity c gravity and inertia* d neither gravity or inertia if you answer all questions right i will give