Which of the following changes lead to a decrease in entropy? a. mixing of pure gases
b. sugar dissolving in coffee
c. melting snow
d. the sublimation (vaporization) of dry ice (solid carbon dioxide)
e. halving the volume of a gas

halving the volume of a gas

Explanation:

Entropy refers to the degree of disorderliness of a system. The greater the volume of a gas, the greater its entropy. The entropy of a system is directly proportional to its volume.

Hence a decrease in the volume of a gas leads to a decrease in its entropy. Ultimately, if the volume of a given mass of gas is halved, its entropy decreases according.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.