Is drawing on paper a chemical or physical change

Apiece of metal with a length of 1.42 cm was measured using four different instruments. which of the following measurements is the most accurate?

As air becomes more dense, (select all that apply) o. air weighs less o. gas molecules are closer together o. air is colder o. air weighs more o. gas molecules are further apart o. air is hotter

Ascientist measures the speed of sound in a monatomic gas to be 449 m/s at 20∘c. what is the molar mass of this gas?