Element R and Element Q have the same number of valence electrons. These elements both have similar chemical behavior, but Element R has fewer energy levels than Element Q. Which statement best describes the positions of the two elements in the periodic table?

Some students are using samples of different substances for a lab investigation. They plan to observe the physical properties of each substance and record their observations in a table like the one below. Which of the substances observed are elements?

A student obtains two strips of magnesium, Mg, ribbon that are each 3 cm long. One strip of magnesium is placed in a test tube containing 5 mL of water, and the other strip is placed in a test tube containing 5 mL of hydrochloric acid, HCl. Both liquids are at room temperature. The student’s observations are recorded in the table. Which statement is not supported by the student’s observations?

Four students were given a list of compounds and asked to identify which ones are organic. Which student correctly identified the organic compounds in the list?

Four students were asked to name the parts of an atom that determine the atom’s identity and chemical properties. The students’ responses are shown in the table below. Which student’s responses are correct?

A chemical reaction in which calcium carbonate, CaCO3, is decomposed results in the production of two simpler compounds. What mass of calcium carbonate, to the nearest hundredth of a gram, is decomposed in this reaction?