It's considered a chemical change because the whitish substance is now newly produced.
Answer:
The correct answer is -
Independent Variable: change of speed
Dependent Variable: time takes to stop
Controlled Variables: stop at a stop sign
Explanation:
To know the effect of the speed to take the time to stop at a stop sign Bobbye perform this exercise where he changes the speed at each time that he is driving to know the time it takes to stop at a stop sign. There is a change that takes place purposely is in the speed of driving so it is an independent variable as the independent variable is a variable that is manipulated in an experiment or investigation.
The time it takes to stop is the factor that depends on the speed so it is the dependent variable as the dependent variable is the variable that depends on the independent variable.
The control variable remains the same or constant in an investigation which is stoping at a stop time irrespective of speed.
Answer:
Arranged in order of most soluble to least soluble in water:
Explanation:
Water is a polar solvent due to the electric charge it possesses. Hence it would only dissolve polar molecules.
Non-polar molecules would be dissolved by non-polar solvents.
Short chain alcohols are more soluble than butanol, but generally the polar -OH group is soluble in water.
Hey there!
NaHCO₃
Notice that there is no subscript under Na.
That means there is one atom of Na for each molecule of NaHCO₃.
Hope this helps!
In an average mass, each entry has equal weight. In a weighted average, we multiply each entry by a number representing its relative importance.
Assume that your class consists of 15 girls and 5 boys. Each girl has a mass of 54 kg, and each boy has a mass of 62 kg.
<em>Average mass</em> = (girl + boy)/2 = (54 kg + 62 kg)/2 = <em>58 kg</em>
<em>Weighted average (Method 1)
</em>
Use the <em>numbers of each</em> gender (15 girls + 5 boys)
,
Weighted average = (15×54 kg + 5×62 kg)/20 = (810 kg + 310 kg)/20
= 1120 kg/20 = <em>56 kg</em>.
If you put all the students on one giant balance, their total mass would be
1120 kg and the average mass of a student would be <em>56 kg.
</em>
<em>Weighted average (Method 2)
</em>
Use the <em>relative percentages</em> of each gender (75 % girls and 25 % boys).
Weighted average = 0.75×54 kg + 0.25×62 kg = 40.5 kg + 15.5 kg = <em>56 kg</em>
Each girl contributes 40.5 kg and each boy contributes 15.5 kg to the <em>weighted average</em> mass of a student.
