Which of the following investigations is an experiment? 1 Constructing a model to study the water cycle

2 Measuring the height of a table using a measuring tape

3 Measuring the effect of different activities on heart rate

4 Observing two birds to find out which of the two flies higher

If an astronaut takes an object to the moon the following is true (choose only one). a the mass will change but the weight will be the same. b both the mass and the weight of the object will be the same. c the weight will change but the mass will be the same. d both the mass and the weight of the object will change.

(**i would really appreciate if this was answered soon** ) which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?

Which additional product balances the reaction h2so4 + 2naoh → na2so4 + 2h2o 2oh h2o2 h3o