Why can't the efficiency of a heat engine be 100%?

What is the atomic mass of an element?

Do winds and currents flow faster at the equator than at the poles, or more slowly? Think about what you know regarding the shape and rotation of the Earth, the directions of currents, and convection. Make inferences from what you know.

What characteristics of the medium determine the speed of sound? How would raising the pitch of a singing voice affect the speed with which the song is carried through the room?

A zero-order reaction has a constant rate of 2.30*10-4 M/s. If after 80.0 seconds the concentration has dropped to 1.50*10-2 M, what was the initial concentration?

There are three crates being pushed over a concrete floor by a horizontal force, There are three crates being pushed over a concret, of magnitude 440 N. The masses of the crates are m1=30.0 kg, m2=10.0kg, m3=20.0kg.

In a series circuit, loads which have the same voltage dropped across them will have?.

When a brick is dropped from the roof of a house, it lands on the ground with a speed v. What will the speed at ground level be for an identical brick dropped from a roof twice as high as the first one?

The scientific method begins with recognizing a problem. The recognized problem in this scenario is, "Why is the printer in the office not working?" Choose the hypotheses that are testable and from which an experiment can be formed.

The correctly balanced equation for H2O2 → H2O + O2 is

How would an unbalanced chemical equation convey misleading information about what took place during a chemical reaction?