Changes Around Us - Class 6 Notes & Olympiad Questions

Solved Questions on Changes Around Us

1. Consider the following statements and choose the correct option:

Statement I: Phases of the moon are periodic changes.
Statement II: Earthquakes are non-periodic changes.

a) Statement I is correct but statement II is incorrect.
b) Statement I is incorrect but statement II is correct.
c) Both statements are correct.
d) Both statements are incorrect.

Answer: c) Phases of the moon occur in a regular and repeating pattern, making them periodic changes. Earthquakes, on the other hand, are non-periodic changes because they do not occur at regular intervals and their timing and intensity are unpredictable.

2. To understand the properties of water, a student filled two identical containers with water. One container was kept at room temperature, and the other was placed in the freezer. After some time, the student observed that the container in the fridge cracked. What can be concluded from this observation?

a) Water contracts when it freezes.
b) Water expands when it freezes.
c) The containers were not suitable to carry out the experiment
d) Water cannot freeze in a container.

Answer: b) The observation that the container in the freezer cracked indicates that the water expanded upon freezing. Unlike most substances, water expands when it freezes. This expansion can exert pressure on the container, causing it to crack or break. This property of water is known as "anomalous expansion".

3. To demonstrate the expansion of a substance upon heating, which material can be used?

a)
b)
c)
d)

Answer: a) When we heat certain materials, they tend to expand. One material that can be used to demonstrate this expansion property is metal. Metals have the ability to expand significantly when heated.

4. Fill in the blank:

When a candle burns, it is an example of a __________ change.

a) physical and reversible
b) physical and irreversible
c) chemical and reversible
d) chemical and irreversible

Answer: d) When a candle burns, it undergoes a chemical change because the wax reacts with oxygen in the air to produce heat, light, and various gases. This change is irreversible because the original wax cannot be easily recovered or converted back into its original form.

5. Match the following types of changes with their descriptions.

a) 1:C, 2:A, 3:B, 4:D
b) 1:A, 2:C, 3:B, 4:D
c) 1:C, 2:A, 3:D, 4:B
d) 1:A, 2:C, 3:D, 4:B

Answer: c) Exothermic Change: Release of heat in the environment
Endothermic Change: Absorption of heat
Periodic Change: Changes that repeat at regular intervals of time
Non-periodic Change: Changes that do not repeat at regular intervals of time

FAQs

1. What are natural changes in the environment?

Seasons, climatic changes and natural disasters like earthquakes and volcanic eruptions are examples of how the environment changes naturally.

2. What is climate change, and how does it affect us?

Permanent changes to temperature and weather patterns are referred to as climate change. It may result in extreme changes in the weather, elevated sea levels, and ecological disturbances that impact plant and animal life.

3. What are the examples of endothermic change?

Here are some examples of endothermic change:

1. Melting Ice: Imagine taking an ice cube from the freezer. As it turns into water in your hand, it's absorbing heat from the environment. This is an endothermic change.

2. Baking Cookies: When you help in baking cookies at home, the dough transforms into delicious cookies in the oven. This process is endothermic as it absorbs heat during the baking.

3. Photosynthesis in Plants: In science class, you learn about photosynthesis in plants. This is an endothermic process where plants absorb sunlight to make their own food.

4. Cooling Effect of Evaporation: On a hot day, sweating helps cool your body. The water on your skin evaporates, taking in heat from your body, providing a refreshing sensation. This is an endothermic change.

5. Using an Instant Cold Pack: If you've ever used an instant cold pack for a bump or bruise, you're witnessing an endothermic change. The chemicals inside the pack absorb heat, creating a cold sensation.

6. Dissolving Salt in Water: During a science experiment, when you dissolve salt in water, the process is endothermic. The salt absorbs heat from its surroundings to dissolve in the water.

4. What are the examples of periodic and non periodic changes?

Here are some examples of periodic and non periodic changes:

Examples of Periodic Changes

1. Day and Night Cycle: The rotation of the Earth leads to a consistent pattern of day and night, making it a periodic change.

2. Seasonal Changes: The Earth's orbit around the Sun causes seasonal variations, with cycles of spring, summer, autumn, and winter representing periodic changes.

3. Moon Phases: The changing appearance of the moon in the night sky, from full moon to new moon and back, is a periodic change driven by the moon's orbit around the Earth.

4. Tides: The rise and fall of ocean tides are periodic, influenced by the gravitational pull of the moon and the sun on Earth.

Examples of Non-Periodic Changes

1. Volcanic Eruptions: Volcanic eruptions are non-periodic, occurring irregularly based on geological conditions and build-up of pressure beneath the Earth's surface.

2. Earthquakes: Earthquakes are non-periodic events caused by the sudden release of energy in the Earth's crust, with no predictable cycle.

3. Forest Fires: Forest fires are non-periodic and typically result from a combination of dry conditions, human activities, and lightning strikes.

4. Meteorite Impacts: Meteorite impacts on Earth are non-periodic events that happen randomly when celestial bodies collide with our planet.

5. What is the role of technology in bringing about changes in our daily lives?

Technology plays a important role in shaping our daily lives by introducing innovations, improving communication, and contributing to advancements in various fields such as medicine, education, and transportation.