Balance these equations:

HgO → Hg + O2

Na + HCl → H2 + NaCl

K + Cl2 → KCl

C2H6 + O2 → CO2 + H2O

C5H12 + O2 → CO2 + H2O

C6H14 + O2 → CO2 + H2O

What object did you choose to put on the skateboard

Why is Einstein's description of gravity called a theory, while Newton's is a law?

When you return to Earth after a space mission, you will have aged A. the same as someone who remained on Earth during your mission B. the same as you would if you remained in space C. slightly more than the person who remained on Earth D.

Starting at 9 A. M. you hike for 3 hours at an average speed of 5 mph. You stop for lunch from noon until 3 P. M. What is your average speed over the interval from 9 A. M to 3 P. M.?

What is an example of applying the law of conservation of mass?

Which of the following best characterizes the free energy change ΔG for an endothermic reaction under physiological conditions? A. The sign of ΔG is positive B. The sign of ΔG is zero C. The sign of ΔG is negative D.

In a recent hockey game, one player (m=100kg) was moving at a velocity of 8 m/s when he ran into another player (m=300kg) who was at rest (v=0m/s). After the collision, the two players were stuck together (moving with the same velocity).

In a laser, electrical energy is changed to light energy, and a small amount of the energy is wasted as heat. Describe the total amount of the heat in the system (using the conservation of energy).

What is the name for a star and planets held together by gravity? A. solar system B. galaxy C. black hole D. supernova

When a car turns a corner on a level road, which force provides the necessary centripetal acceleration? 1) gravity 2) normal force 3) air resistance 4) tension 5) friction