Everyday Chemical Changes Practice Questions
19 free Everyday Chemical Changes practice questions for the General Science. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which observation usually indicates that a chemical change has occurred?
- A Change in shape only, nothing else
- B Formation of a new substance
- C Change in size only
- D Change in position
Correct answer: Formation of a new substance
A chemical change results in the formation of one or more new substances. Signs may include gas formation, color change, heat release, or formation of a precipitate.
Rusting of iron is an example of:
- A Physical change
- B Chemical change
- C Melting
- D Evaporation
Correct answer: Chemical change
Rusting forms a new substance called hydrated iron oxide. Because the composition of iron changes, rusting is a chemical change.
Which substances are generally required for rusting of iron?
- A Nitrogen and sunlight
- B Hydrogen and sugar
- C Carbon dioxide and salt only
- D Oxygen and moisture
Correct answer: Oxygen and moisture
Iron rusts when it reacts with oxygen in the presence of water or moisture. Removing either oxygen or moisture can slow down rusting.
Cooking of food is considered a chemical change because:
- A Only the shape and size of the food changes, nothing more
- B New substances with different properties are formed
- C Food only becomes smaller
- D Water only evaporates from food
Correct answer: New substances with different properties are formed
Cooking causes chemical reactions that change the taste, smell, color, and digestibility of food. These changes usually cannot be fully reversed.
Which of the following is an example of fermentation in everyday life?
- A Freezing water into ice
- B Making curd from milk
- C Cutting vegetables
- D Drying clothes
Correct answer: Making curd from milk
Making curd involves bacteria converting milk sugar into lactic acid. This forms a new substance and changes the texture and taste of milk.
Why does a cut apple turn brown when exposed to air?
- A It freezes immediately
- B It undergoes oxidation
- C It absorbs nitrogen only
- D It becomes a metal
Correct answer: It undergoes oxidation
The cut surface of an apple reacts with oxygen in air through enzymatic oxidation. This produces brown-colored compounds on the surface.
Which of the following is a chemical change involving oxygen?
- A Folding a cloth neatly
- B Breaking a glass
- C Burning of a candle
- D Boiling water
Correct answer: Burning of a candle
Burning of a candle involves combustion, where wax reacts with oxygen. It produces new substances such as carbon dioxide and water vapor.
Souring of milk is a chemical change because:
- A Milk only changes its container
- B New acidic substances are formed
- C Milk only becomes colder
- D Milk only changes from liquid to solid water
Correct answer: New acidic substances are formed
During souring, bacteria convert lactose in milk into lactic acid. This changes the composition, smell, and taste of the milk.
Which everyday process is an example of neutralization?
- A Melting butter
- B Filtering tea leaves through a strainer
- C Taking an antacid for acidity
- D Cutting paper
Correct answer: Taking an antacid for acidity
Antacids are mild bases that neutralize excess acid in the stomach. This acid-base reaction forms salt and water.
Which gas is commonly released when baking soda reacts with vinegar?
- A Sulfur dioxide
- B Nitrogen
- C Hydrogen
- D Carbon dioxide
Correct answer: Carbon dioxide
Baking soda reacts with vinegar to produce carbon dioxide gas. The bubbling observed during the reaction is due to this gas formation.
Which of the following changes is usually irreversible?
- A Melting wax
- B Freezing water
- C Dissolving salt in water
- D Burning paper
Correct answer: Burning paper
Burning paper forms ash and gases, which cannot be changed back into the original paper by simple physical methods. This makes it an irreversible chemical change.
Rancidity in oily foods is mainly caused by:
- A Freezing of water
- B Evaporation of salt
- C Oxidation of fats and oils
- D Condensation of steam on the food surface
Correct answer: Oxidation of fats and oils
Rancidity occurs when fats and oils react with oxygen in air. This produces unpleasant smell and taste in food.
Why are chip packets often filled with nitrogen gas?
- A To speed up oxidation
- B To make the chips dissolve completely in water over time
- C To turn chips into sugar
- D To prevent rancidity by reducing oxygen contact
Correct answer: To prevent rancidity by reducing oxygen contact
Nitrogen is relatively unreactive and displaces oxygen from the packet. This slows oxidation of oils and helps prevent rancidity.
Which of the following is an example of a chemical change in digestion?
- A Chewing food into smaller pieces
- B Moving food through the food pipe by muscle contractions
- C Mixing food with water only
- D Breaking down starch into simpler sugars
Correct answer: Breaking down starch into simpler sugars
Digestion involves enzymes breaking complex food molecules into simpler substances. Breaking starch into sugars changes the chemical composition of food.
Which process is a chemical change that releases heat and light?
- A Filtration
- B Sedimentation
- C Combustion
- D Freezing
Correct answer: Combustion
Combustion is a chemical reaction in which a substance reacts with oxygen and releases heat and often light. Burning fuel is a common example of combustion.
Which of the following is a sign of a chemical reaction when an effervescent tablet is added to water?
- A Change in container shape
- B Increase in paper size
- C Formation of bubbles
- D Magnetism
Correct answer: Formation of bubbles
Effervescent tablets produce gas when they react with water. The bubbles are evidence that a chemical reaction is taking place.
Why is lighting a matchstick a chemical change?
- A It only changes the shape and size of the stick
- B It only becomes shorter physically
- C It turns into pure water
- D It produces new substances during burning
Correct answer: It produces new substances during burning
When a matchstick burns, chemicals on its head react with oxygen. This produces heat, light, smoke, and ash, which are new substances.
Which of the following is a chemical change used in baking cakes?
- A Cutting the cake into slices before serving it to guests
- B Cooling the cake after baking
- C Carbon dioxide formation from baking powder
- D Placing the cake on a plate
Correct answer: Carbon dioxide formation from baking powder
Baking powder releases carbon dioxide when heated or mixed with moisture. This gas helps the cake rise and is produced by a chemical reaction.
Which statement correctly describes chemical changes in everyday life?
- A They never form any new substances under normal conditions
- B They always involve only a change in physical shape
- C They often form new substances with different properties
- D They can always be reversed simply by cooling things down
Correct answer: They often form new substances with different properties
Chemical changes involve the formation of new substances with properties different from the original materials. Many daily processes such as cooking, rusting, burning, and digestion are chemical changes.