A student measured a strip of aluminum as 1.25m long. The teacher said it was actually 2.12m long. What was the student's percent error?

41.03 %

Explanation:

Given that,

The actual length of a strip of aluminum is 2.12 m

Observed length of a strip of aluminum is 1.25 m

We need to find the student's percent error. The percentage error on any value is given by :

Putting all values, we get :

So, the percent error of the student is 41.03 %.

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

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.