In which situation does the reactive force between two colliding objects cause a physical change? two bumper cars at an amusement park colliding, causing both cars to change direction

the exhaust from a rocket thrusting the rocket away from the ground

a swing hitting another swing, causing the second swing to move away a baseball player swinging a bat and hitting

a baseball, causing the bat to shatter

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o