According to today's classification system, how many major planets are there in the solar system?

Which jar will roll down an incline in the shortest time, an empty one or one filled with peanut butter?

A) the empty jar B) both reach the bottom at the same time C) the filled jar D) need more information

How many degrees of hardness are defined

on the Mohs hardness scale? a) 3 b) 7 c) 10 d) 12

Tycho Brahe's greatest contribution to astronomy was

a. his model of the universe. b. his telescopic observations. c. his discovery of three laws of motion. d. his 20 years of careful observations of the planets. e. his model of the universe and his telescope observations.

The bolt and nut model shown in this figure represents all but which of the pairs of molecules?

a. CO and CO2 b. H2 and H2O c. NO and NO2