What is the general name given to the type/class of matter that has 100% constant composition?

Identify the following as a metal, nonmetal or semimetal/metalloid:  carbon (C)

Identify the following as an element, compound, homogeneous mixture, or heterogeneous mixture: A magnet composed of Alnico alloy (Al, Ni, Co, Fe, & Cu)

What specific class of matter is a 3% hydrogen peroxide solution?

Based on the molecular diagram below, classify the type of change that is occurring.

What is the term for an investigation that entails performing an experiment, proposing a hypothesis, testing the hypothesis, and ultimately stating a theory or law?

Identify the following as an element, compound, homogeneous mixture, or heterogeneous mixture: sand (SiO2) and sugar (C6H12O6)

A sample of matter changes directly from a solid to a gas without going through the liquid phase. What is the name of this phase change?

Provide a hypothesis for ONE of the following observations: (4 points)(a)  You sneeze every time you visit your friend’s house. OR (b)  On a cold morning, the air pressure in the tires of your automobile measures 34 pounds per square inch. After several hours of high-speed driving the pressure measures 38 pounds per square inch.

Identify the following as a physical property, a chemical property, a physical change, or chemical change: Phosphine is explosive (will explode) when combined with oxygen.