Ahandle or knob is fixed at free end of door. why?

Which is not true about oxygen-17 and oxygen-18?

On mars a rock falls an unknown vertical distance from a resting position and lands in a crater. if it takes the rock 2.5 seconds to fall, how high is the cliff the rock fell from? mars' surface gravity is 3.8 m/s2. a. 9.5 m b. 11.9 m c. 15.2 m d. 23.8 m

Sound travels slower in colder air that it does in warmer air. make a claim about the effect of air temperature on the speed of sound. support your claim with evidence