| A | B |
|---|
| Edmund Halley predicted | that a bright comet was periodic |
| Halley's comet is | retrograde |
| Salmon hatcheries are believed | to have a negative effect on wild salmon |
| The heart has 4 | chambers |
| Heat may be described as | energy in transit |
| Heat added = heat capacity | X change in temperature |
| Heat moves by conduction | convection and radiation |
| A heart beat is | systolic |
| The heart at rest is | diasystolic |
| Hipparchus was one of the most | influential astronomers of antiquity |
| Helen Sawyer Hogg | research variable stars in globular clusters |
| Hormones | proteins, peptides, modified acids and steroids |
| The Hubble Space telescope | is in orbit |
| Demographic transition is a shift | from high birth and death rates |
| Hydro electricity provides | 20% of the world's electricity |
