1.
What is an acid?
Correct Answer
B. A substance that produces H+ ions when added to water
Explanation
The correct answer is "A substance that produces H+ ions when added to water". This is because acids are known to release hydrogen ions (H+) when dissolved in water, which is why they are also referred to as proton donors. This characteristic of acids is what gives them their acidic properties, such as the ability to corrode metals and react with bases to form salts.
2.
What is an alkali?
Correct Answer
C. A soluble base
Explanation
An alkali is a substance that is soluble in water and can neutralize an acid. It is a type of base that produces OH- ions when dissolved in water. This allows it to react with acidic substances, forming water and a salt. Therefore, an alkali is a soluble base that can neutralize acids.
3.
A substance with a pH of 6 is...
Correct Answer
A. A weak acid
Explanation
A substance with a pH of 6 is considered a weak acid because it is slightly acidic. pH values range from 0 to 14, with 7 being neutral. Anything below 7 is considered acidic, and the lower the pH value, the stronger the acid. Since a pH of 6 is only slightly acidic, it is classified as a weak acid.
4.
Pick the correct equation for the reaction between hydrochloric acid and iron oxide.
Correct Answer
A. Hydrochloric acid + solid iron (III) oxide → iron (III) chloride solution + water
Explanation
The correct equation for the reaction between hydrochloric acid and iron (III) oxide is Hydrochloric acid + solid iron (III) oxide → iron (III) chloride solution + water. This is because hydrochloric acid reacts with iron (III) oxide to form iron (III) chloride and water. The Roman numeral III in parentheses indicates the oxidation state of iron in the compound.
5.
We can react an acid and an alkali together to produce a salt. The correct name for this type of chemical reaction is...
Correct Answer
D. Neutralisation
Explanation
Neutralisation is the correct name for the chemical reaction that occurs when an acid and an alkali are combined to produce a salt. During this reaction, the acid donates a hydrogen ion (H+) to the alkali, which accepts it to form water. The remaining ions from the acid and alkali combine to form a salt. This reaction is called neutralisation because it results in the formation of a neutral substance, water, from the combination of an acid and an alkali.
6.
When an acid and an alkali react, a salt and water are formed. Pick the correct salt produced when ammonium hydroxide reacts with nitric acid.
Correct Answer
B. Ammonium nitrate
Explanation
When ammonium hydroxide (NH4OH) reacts with nitric acid (HNO3), the salt produced is ammonium nitrate (NH4NO3). This is because the ammonium ion (NH4+) from ammonium hydroxide combines with the nitrate ion (NO3-) from nitric acid to form the salt ammonium nitrate.
7.
Salts can also be made by reacting metals with acids. What gas is given off when a metal reacts with an acid?
Correct Answer
C. Hydrogen
Explanation
When a metal reacts with an acid, the gas given off is hydrogen. This is because metals are more reactive than hydrogen, so they displace hydrogen from the acid. The reaction between a metal and an acid results in the formation of a salt and the release of hydrogen gas.
8.
Precipitation reactions occur when an insoluble salt is formed. Precipitation reactions can be used in industry to...
Correct Answer
A. Remove some substances from waste water
Explanation
Precipitation reactions occur when an insoluble salt is formed. In the context of waste water treatment, precipitation reactions can be used to remove some substances from the water. This is achieved by adding a specific reagent that reacts with the substances in the water, forming insoluble salts. These insoluble salts then precipitate out of the water, allowing for their easy removal. This process helps to purify the waste water by removing harmful or unwanted substances, making it safer for disposal or reuse.
9.
A strong acid...
Correct Answer
D. Is 100% ionised in water
Explanation
A strong acid is 100% ionized in water because it completely dissociates into ions when dissolved in water. This means that all of the acid molecules break apart into their constituent ions, which allows them to conduct electricity and exhibit strong acidic properties. This is in contrast to a weak acid, which only partially ionizes in water and does not completely dissociate into ions. Therefore, the answer "is 100% ionized in water" is the correct explanation for a strong acid.
10.
Pick the correct combination of definitions.
Correct Answer
B. Acid - proton donor
Alkali - proton acceptor
Explanation
In chemistry, an acid is a substance that donates protons (H+) during a chemical reaction. It increases the concentration of H+ ions in a solution. On the other hand, an alkali is a substance that accepts protons (H+) during a chemical reaction. It decreases the concentration of H+ ions in a solution. Therefore, the correct combination of definitions is "Acid - proton donor" and "Alkali - proton acceptor".