Heating a substance causes molecules to speed up and spread slightly further apart, occupying a larger volume that results in a decrease in density. Cooling a substance causes molecules to slow down and get slightly closer together, occupying a smaller volume that results in an increase in density.
From: www.middleschoolchemistry.com
Answer:

Explanation:

The incomplete combustion of alkanes, and other fuels actually, happens when there is a limited supply of oxygen. Instead of the fuel burning completely to produce carbon dioxide, it produces carbon monoxide instead.
This gas is harmful to jumans because it combines with haemoglobin in lood and takes up space that belongs to oxygen which can lead to suffocation or even death
Answer:
Ok so the answer for 9 is
x/6=4
x=24
Explanation:
Solve for x by simplifying both sides of the equation, then isolating the variable.
The correct answer is A. The magnetic field is strongest at the north pole and the south pole of a bar magnet. At the poles, the magnetic field is equally strong while the force is weaker at the middle of the bar. The field lines are closely packed at each pole and it gets wider as the lines get further from the pole.