Which one of the following is a double-displacement reaction?
a.) 2li (s) + znso4 (aq) → li2so4 (aq) + zn (s)
b.) hno3 (aq) + koh (aq) → h2o (l) + kno3 (aq)
c.) fe (s) + cuso4 (aq) → feso4 (aq) + cu (s)
d.) 2cu (s) + o2 (g) → 2cuo (s)

In which of the following cases is work being done on an object? question 2 options: pulling a trailer up a hill carrying a box down a corridor suspending a heavy weight with a strong chain pushing against a locked door

Arod of some material 0.20 m long elongates 0.20 mm on heating from 21 to 120°c. determine the value of the linear coefficient of thermal expansion [in (degrees c)^-1] for this material.

Sawyer is studying diffraction. he draws a diagram of a plane wave to show how light waves travel. which best describes sawyer’s error? the wave fronts should be perpendicular to the direction in which the waves move. the arrow showing the direction of movement of the waves should be pointing to the left. the arrow showing the direction of movement of the waves should be pointing downward. the wave fronts should be both parallel and perpendicular to the direction in which the waves move.