Homework Practice

Printable assignment

Final Assessment: Acids, Bases and Salts

Section A: Concepts and Classification

Question 1mcq

Which set contains only acidic substances commonly discussed in Grade 7?

A.Lemon juice and vinegar

B.Soap solution and baking soda solution

C.Distilled water and salt solution

D.Lime water and washing soda solution

Question 2mcq

Litmus is called an indicator because it:

A.neutralises every acid completely

B.shows different colours in acidic and basic solutions

C.is always a strong base

D.forms crystals from hot solution

Question 3mcq

Red litmus remains red in solution A. Blue litmus turns red in solution A. What is A?

A.Basic

B.Neutral

C.Acidic

D.A salt that cannot dissolve

Question 4mcq

Which word equation correctly represents neutralisation?

A.Acid + Salt

ightarrow

Base + Oxygen

B.Base + Water

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Acid + Wool

C.Indicator + Acid

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Metal + Water

D.Acid + Base

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Salt + Water

Question 5mcq

Factory waste is acidic. Before releasing it safely after treatment, what should be done?

A.Neutralise it with a suitable basic substance under controlled conditions.

B.Add more acid to increase acidity.

C.Add turmeric only and release it immediately.

D.Heat it until it changes colour, ignoring pH.

Question 6mcq

A product of acid-base neutralisation is called a salt. Which example is a salt?

A.Lemon juice

B.Sodium chloride

C.Soap foam

D.China rose extract

Section B: Litmus and Neutralisation

Question 7mcq

During an activity, a few drops of acid fall on the table. What should a student do first?

A.Wipe it with bare hands quickly.

B.Taste it to identify the acid.

C.Inform the teacher and follow lab safety instructions.

D.Mix it with random chemicals to see bubbles.

Question 8mcq

An unknown solution turns turmeric paper reddish-brown and red litmus blue. What conclusion is best?

A.The solution is acidic.

B.The solution is neutral.

C.The solution is definitely distilled water.

D.The solution is basic.

Question 9mcq

Which observation best identifies a neutral solution using litmus?

A.No change in either red or blue litmus

B.Blue litmus turns red

C.Red litmus turns blue

D.Both papers dissolve immediately

Question 10mcq

A student wants to test whether soap solution is basic. Which indicator result would support this?

A.Blue litmus turns red.

B.Turmeric turns reddish-brown.

C.Red litmus remains red and blue litmus turns red.

D.China rose has no possible colour change.

Question 11mcq

Solution X turns red litmus blue. Solution Y turns blue litmus red. Which comparison is correct?

A.X is acidic and Y is basic.

B.Both are neutral.

C.X is basic and Y is acidic.

D.Both are indicators.

Question 12mcq

Why is heat often noticed during neutralisation?

A.Indicators always generate electricity.

B.Salt crystals always burn.

C.Water absorbs all acids without reaction.

D.Neutralisation is a reaction that can release heat.

Section C: Daily Life and Safety

Question 13mcq

Which daily-life pair correctly matches problem and neutralising substance?

A.Excess stomach acid — antacid

B.Ant sting acid — more lemon juice

C.Acidic soil — vinegar

D.Basic soil — washing soda only

Question 14mcq

A salt is not necessarily table salt only. Which reasoning supports this?

A.Every salt has the same chemical formula.

B.Many different acids and bases can form different salts.

C.Only sodium chloride can be produced in reactions.

D.All salts are indicators.

Question 15mcq

Which label should be placed on a bottle used for a school acid-base activity?

A.Safe to drink if colourless

B.Touch directly to check strength

C.Do not taste; use only under teacher supervision.

D.Mix freely with unknown liquids

Question 16mcq

A student tests solution M: blue litmus stays blue, red litmus turns blue. What should the lab report say?

A.M is acidic because blue litmus stayed blue.

B.M is neutral because only one paper changed.

C.M is unsafe to classify from any observation.

D.M is basic because it turns red litmus blue.

Question 17mcq

Which statement is a misconception?

A.All acids are dangerous to touch in any amount and all bases are safe.

B.Acids can be found in lemon and vinegar.

C.Bases can be found in soap solution.

D.Neutral substances are neither acidic nor basic.

Question 18mcq

Why should a student use only a few drops of indicator?

A.More indicator always makes the answer more correct.

B.A small amount is enough to show colour change and avoids wastage/contamination.

C.Indicator must replace the whole solution.

D.Indicators work only when tasted.

Section D: Reasoning Challenge

Question 19mcq

A diagram shows two strips: red litmus becomes blue, blue litmus remains blue. Which label should be under the beaker?

A.Acidic solution

B.Neutral solution

C.Basic solution

D.Pure acid only

Question 20mcq

If equal suitable amounts of acid and base are mixed, why might the final solution become neutral?

A.The acid disappears physically without reaction.

B.The base changes into sugar.

C.The indicator absorbs all water.

D.The acid and base cancel each other’s effects through neutralisation.

Question 21mcq

A toothpaste advertisement says it helps fight acids produced in the mouth. Which concept is being used?

A.Neutralisation by mild basic substances

B.Crystallisation of sugar

C.Rusting of teeth

D.Condensation of saliva

Question 22mcq

In “acid + base

ightarrow

salt + water”, which part helps identify the salt?

A.It is always the sour reactant.

B.It is the product other than water formed in neutralisation.

C.It is the indicator added before reaction.

D.It is the gas released by every reaction.

Question 23mcq

Which safety mistake should be corrected immediately?

A.A student wears goggles during testing.

B.A student uses a dropper for small samples.

C.A student smells an unknown acid by placing the nose directly over the test tube.

D.A student washes hands after the activity.

Question 24mcq

Case: Solution A turns blue litmus red. Solution B makes turmeric reddish-brown. Which statement is most justified?

A.A and B are both neutral.

B.A is basic and B is acidic.

C.No conclusion can be drawn from indicators.

D.A is acidic and B is basic.