Answer:
Touching, Smelling.
Explanation:
Touching will be useful to detect stimuli like coldness and hotness.
Smelling on the other hand will help to make observations on smell and change in smell. These two are among the five senses that we use to make observations as we record what we see, hear, touch and feel, smell and taste.
The answer is With precipitation
I would say it is a hydrogen bond
Answer: The atoms in a gas move at high speed.
The atoms in a gas spread in all directions.
A gas is a state of matter in, which atoms remains in a constant motion, they do not stick together. They are free and can move in all directions. The gas molecules expands to fill the available space. Hence, they can change shape and volume. The gas atoms being in a molecular state moves fast in high speed to break away from each other, to remain in a free state.
The answer is either the second one or the fourth one.