A student wants to determine whether an unknown solid is an ionic compound. He puts some in water and finds that it does not dissolve. He says that this proves the solid is ionic. Which best evaluates the student's reasoning? (2 points)
He is incorrect, because water can dissolve ionic solids.
The test proves nothing, because water dissolves all solids.
He is correct, because polar liquids cannot dissolve ionic solids.
The test proves nothing, because it only shows that the solid is a compound.
23.
Which characteristic would you predict from a solution that has a pH of 5? (2 points)
Sour taste
Very high concentration of hydroxide ions
Slippery feeling
Very low concentration of hydronium ions
24.
A student measures the pH of a solution to be 6.8. Which should the student add if she wants to decrease the pH of the solution? (2 points)
NaCl
H2O
HF
KOH
25.
What property of a solution causes an acid-base indicator to change to different colors? (2 points)
Different temperature
Different amounts of surface tension
Different levels of hydrogen bonding
Different concentrations of hydronium ion
26.
Which is a not scientific question? (2 points)
What is the pH of a solution of potassium hydroxide?
Which base is the most exciting to study?
Will HF neutralize a solution of HCl?
Does adding sodium chloride change the pH of a solution?
27.
A scientist mixes an unknown powder into a beaker of water. He then uses an indicator and finds that the pH of the resulting solution is 8.5. What can he infer from this observation? (2 points)
The unknown powder was acidic.
The unknown powder decreased the hydrogen ion concentration of the water.
The indicator used can measure only basic solutions.
The powder contains hydrogen ions.
28.
Which is a chemical property of mercury? (2 points)
Boiling point of −39ºC
Silvery color
Liquid at room temperature
Reacts with oxygen
29.
How many oxygen atoms are present in one molecule of nickel hydroxide, Ni(OH)2? (2 points)
1
2
3
4
30.
An industrial process involves reacting nitrogen gas (N2) and hydrogen gas (H2) to produce ammonia (NH3). What type of reaction is this? (2 points)
Decomposition reaction
Double-replacement reaction
Single-replacement reaction
Synthesis reaction