18. c
19. A
20. decomposition reaction
21. 4
22. 0.04%
Answer: The given statement is true.
Explanation:
Entropy means the measure of randomness present in a substance. That is, an increase in temperature will lead cause more motion in the particles of a substance more will be their kinetic energy.
As a result, there will occur more collisions due to which randomness of molecules will increase. Hence, there will be increase in entropy.
So, when we decrease the temperature then there will be decrease in motion of particles. As a result, lesser number of collisions will take place between them. Hence, degree of randomness will also decrease.
Thus, we can conclude the statement entropy of a system decreases with decrease in temperature, is true.
1. <em>Increasing the concentration of one or more reactants will often increase the rate of reaction. This occurs because a higher concentration of a reactant will lead to more collisions of that reactant in a specific time period. </em>
<em>2. Physical state of the reactants and surface area.</em>
Answer:
5000g
Explanation:
mass= density × volume
Since the unit of density here is g/mL, we need to convert the volume to mL.
1L= 1000mL
4L= 4 ×1000 = 4000 mL
Mass of object
= 1.25 ×4000
= 5000g
Answer: There are 7.4 moles of helium gas present in a 1.85 liter container at the same temperature and pressure.
Explanation:
Given: 
= 2.25 L, 
= 9.0 mol
= 1.85 L, 
= ?
Formula used to calculate the moles of helium are as follows.
Substitute the values into above formula as follows.
Thus, we can conclude that there are 7.4 moles of helium gas present in a 1.85 liter container at the same temperature and pressure.
