Answer:
Air is a mixture. Its constituents can be separated. For example: oxygen, nitrogen etc.
Hydrochloric acid is a mixture, being an acidic liquid.
Answer:
Velocity
Explanation:
The change of velocity rate it's the definition of acceleration.
While increasing or decreasing velocity, it means that an acceleration it's happening.
Using some math:

This can be read as "the acceleration it's equal to te variation of velocity with respect to time"
Answer:
12 moles
Explanation:
1. Do comparison
From the equation, 1 mole of C3H8 yields 3 moles of CO2
Therefore, 4 moles of C3H8 should yield 12 moles of CO2
Steps:
Number of moles of CO2
= (1 mol x 4) x 3
= 12 moles