Substance is some matter (it can be solid liquid or gas) that has its own properties.. everything in this world are substances...
like for example: the bread that we consume has - wheat ..yeast.. sugar.. salt or some other substances
You would have to place your sensor above earth's atmosphere because it blocks out nearly all x-rays. this is why we have the Chandra observatory
hope this helps
Answer:
Explanation:
Given
Each student exert a force of 
Let mass of car be m
there are 18 students who lifts the car
Total force by 18 students 
therefore weight of car 
mass of car 
(b)
Answer:
It is formed by a horizontal number line, called the x-axis, and a vertical number line, called the y-axis.
Explanation:
