B, radon is correct. Interestingly, it often collects in basements from radioactive decay of rocks such as granite that contain uranium. Because it is an unreactive noble gas and because it is denser than air it sits in basements and must be pumped out. It collects in human lungs and is the second leading cause of lung cancer behind smoking.
Answer:
1. False
Balanced forces would mean all forces acting upon an object would be equal. So there is no movement.
2. True
Unbalanced forces would mean there is a force acting upon a side of tge object, causing it to move in a direction.
Answer:
D
Explanation:
A The calcium chloride dissolves in solution
B The mass of the solution totals 20 g
C The temperature of the solution is 35 degrees
D The solution became lighter in color
The correct answer would be that <u>the solution became lighter in color.</u>
An increase in temperature can also be considered a sign of a chemical reaction but in this case, the dissolution of calcium chloride in water is in itself exothermic.
A change in the mass of the final solution could also be considered a sign of a chemical reaction but in this case, the total mass equals the addition of the individual masses of the reactant.
The dissolution of calcium chloride in water is not enough as evidence of a chemical reaction. Dissolution can be a physical change of which, the evaporation of the water would retrieve the solute.
<em>A change in color, however, is one of the evidence to establish that a chemical reaction has occurred.</em>
The correct option is D.
