The block’s average speed : 0.36 m/s
<h3>Further explanation</h3>
Distance is the length traveled by an object within a certain of time .
Average speed = total distance/total amount of time ,
Can be formulated :

ΔD= total distance
Δt= total time
A block is pulled 0.90 m to the right in 2.5 s :
ΔD= total distance = 0.9 m
Δt= total time = 2.5 s
The block’s average speed :

Earth's atmosphere is 78% nitrogen, 21% oxygen, 0.9% argon, and 0.03% carbon dioxide with very small percentages of other elements. Our atmosphere also contains water vapor. In addition, Earth's atmosphere contains traces of dust particles, pollen, plant grains and other solid particles.
Answer: A. True
Explanation: Combustion is a chemical process in which a substance reacts rapidly with oxygen and gives off heat. The original substance is called the fuel, and the source of oxygen is called the oxidizer. ... During combustion, new chemical substances are created from the fuel and the oxidizer.
Answer:
Pressure that is exerted by one gas as if it occupied a container by itself.
Metals react with ______ to form compounds that are alkaline.
A. metalloids
B. oxygen (O)
C. non-metals
D. hydrogen (H)
The answer is D, Hydrogen (H).