Scientific investigations most often start from observations of the natural world and which of the following? Models, computers, variables, questions

Which is classified as a salt ammonia or sodium chloride?

Which substance accounts for nearly 80 percent of Earth's atmosphere? A. oxygen B. nitrogen C. carbon dioxide D. argon

The pressure of a gas at 10 degrees Celsius is greater than the pressure of the gas at 30 degrees Celsius. 1) True 2) False

At the high temperature at which this reaction takes place, a green-yellow solid may also be formed. Propose a hypothesis about the chemical nature of this product.

The maximum depth of Lake Tahoe is 99.6 rod. How deep is Lake Tahoe in fathoms if one fathom-0.364 rod? ball part 250-300 fathom

How are amounts of hydrogen and oxygen gas made from the electrolytic decomposition of water related to the chemical formula of water?

Hydrogen peroxide decomposes to water and oxygen at constant pressure by the following reaction: 2H2O2 (l) → 2H2O (l) + O2 (g) ΔH = - 196 kJ Calculate the value of q (kJ) in this exothermic reaction when 3.

What is the concentration of hydronium in each of the following cases: [OH-] = 10-12 M? [OH-] = 10-2 M?

Which statement best explains why elements are matter? An element is a physical substance that has mass and takes up space. Elements are pure substances that cannot be divided chemically. Each element is a pure substance composed of one type of atom.

Which of the following best describes what causes the phases of the moon? The alignment of the sun, Earth, and moon The speed of the moon around the Earth The speed of the Earth around the sun The alignment of the planets