Which is true about a pure substance? A. An element is a pure substance because its melting point decreases when its mass decreases.

B. A compound is a pure substance because it has a single chemical composition.

C. A mixture is a pure substance because its parts can be visibly identified.

D. A solid is a pure substance because it has a higher density than a liquid.

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.

answer: glucoamylase presented optimum activity at temperature of 55â°c, and, in the glycosidic bonds from the non-reducing ends of starch, resulting in the production of glucose. source and type of fermentation can affect the enzyme's properties

credit to kalahira