In a four-stroke engine, the timing gears control a. the amount of fuel that reaches the cylinder. b. when the spark plug fires. c. when the valves open and close. d. the speed of the air flow through the carburetor.

1. calculate the approximate enthalpy of the reaction in joules. estimate that 1.0 ml of vinegar has the same thermal mass as 1.0 ml of water. iqnore the thermal mass of th sodium bicarbonate. note: it takes about 4.2 joules () to change 1.0 gram (1.0ml) of water 1.0 c

Which of the following statements is true? a. elements in the last period are radioactive. b. atomic weight is the same as atomic mass. c. elements in the same group have the same number of electron shells. d. atomic number equals the number of neutrons in the nucleus of an atom.

0.09 moles of sodium sulfate in 12 ml of solution