A law is statement about an observed concept. A theory involves the explanation of scientific concepts or principles. A hypothesis is the predicted explanation about some concepts that has to be tested in order to prove it to be right. An observation is the observing the results of a scientific experiment carried out to test an hypothesis.
Here the given statement 'A chemist mixes sodium with water and witnesses a violent reaction between the metal and water,' can be classified as an observation as it explains what the chemists observes as a result of his chemical experiment or test..
Answer: True
The formula of weight is w = mg, where m is the mass and g is the acceleration of gravity. If you want to calculate an object's weight, you need to know the two components: mass and gravity.
You only need to know the mass of the object because the acceleration of gravity is ALWAYS (assuming the object is on Earth) 9.8 m/s^2.
