you've made the hypothesis that the higher the density of a rock, the higher the temperature at which it will melt, because a denser rock contains more material.
what is one thing that you should control in an experiment designed to test this hypothesis?
a. the color of each rock
b. the weight of each rock
c. the density of each rock
d. the temperature at which each rock melts

C. The density of each rock

1: most common garden plants prefer loam — soils with a balance of different-sized mineral particles (approximately 40% sand, 40% silt, and 20% clay) with ample organic matter and pore space. however, some plants grow better in sandy soils, while others are well-adapted to clay soils.

2: available water capacity is the maximum amount of plant available water a soil can provide. it is an indicator of a soil's ability to retain water and make it sufficiently available for plant use. available water capacity is the water held in soil between its field capacity and permanent wilting point.

3: it is the same for all living things (plants and animals). it also includes very tiny organisms that our eyes cannot see. they are known as microorganisms, and include viruses, bacteria and fungi.