Mrs. Sprague wants to determine which type of ball has the highest bounce. she drops a tennis ball, soccer ball, then a basketball from a height of 15 feet, and
measures and records how high each type of ball bounces back up.
In this experiment, what is a constant variable?

A. the height from which the ball is released
B. the bounce height
C. the different types of balls

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6

that tool would be a compass