Answer:
don't understand your language
Answer:
B. Controlled variables
Explanation:
The Dependent sample t-test compares the mean score of measurements in one group to that of another other group. It mainly used when analyzing comparable sample units as it pairs repeatable observations within a time frame.
Controlled variables are factors that are not tested and remain constant. Some examples of controlled variables are temperature, pressure, volume etc
Answer:
The accuracy can be improved by making sure no external force is applied, i.e the marbles should accelerate under gravity only during each trial.
Explanation:
Accuracy is a term used to describe the relationship between a measured value to the real value. When a measured value is accurate, it implies that there is little or no error in the value; thus it is equal to the real value or very close to it.
Since this experiment is to determine the speed with which the marble roll down the plane, they should ensure uniform acceleration through out the trials. The marbles should be allowed to move under the influence of gravity only without applying any external force.
In classifying salts as neutral, acidic, or basic, it is important to take note of the strength of the acids and bases that they come from. A strong acid and strong base produce a neutral salt. A weak acid and strong base produce a basic salt. A strong acid and weak base produce an acidic salt. So the answers must be:
KCl = neutral (from HCl and KOH)
NH4Br = acidic (from NH4 and HBr)
K2CO3 = basic (from KOH and H2CO3)
NaCN = basic (from NaOH and HCN)
LiClO = basic (from LiOH and HClO)