NCERT MCQ Solutions for Class 5 EVS Looking Around Chapter 15 Blow Hot, Blow Cold

The story was written by Dr. Zakir Hussain, a former President of India. He was also a renowned educator and the author of many stories for children.

When a person’s hands are cold, blowing on them transfers heat from their warm breath to their skin. This is a simple, common way to warm up numb fingers.

It can seem confusing that the same air blown from our mouths can be used to warm something cold (like hands) and to cool something hot (like food).

Blowing on hot food creates moving air that carries heat away from its surface more quickly. This process of convection helps the food to cool down faster.

Our breath contains warm, moist air. When this air hits a cold surface like a mirror, the moisture condenses into tiny water droplets, making the mirror look hazy.

You can measure your breathing rate by counting breaths per minute while at rest. Then, after exercising, count them again to see how much faster you breathe.

Musical instruments produce sound in different ways. A guitar is a string instrument, which makes sound when its strings are plucked, unlike wind or percussion instruments.

Blowing warm breath onto a folded cloth makes it a gentle, warm compress. The warmth can provide comfort and help soothe the pain of a minor bump or bruise.

The paper snake spins to show the direction of air movement. It spins one way when hot air rises (convection) and the opposite way when cool air sinks.

Blowing on spectacle lenses deposits a fine layer of moisture. This moisture helps to loosen dust and smudges, making them easier to wipe away cleanly with a cloth.

When you breathe in (inhale), your lungs fill with air and your rib cage moves up and out. This causes your chest to expand and its measurement to increase.

A stretched balloon is under high tension. When air is blown across it, it vibrates more intensely than a flimsy paper wrapper, producing a louder whistling sound.

The story primarily demonstrates principles of heat transfer. It shows how air from our lungs can be used to either warm up or cool down objects, depending on temperatures.

When you exercise, your muscles work harder and need more oxygen. Your body responds by making you breathe faster and deeper to supply this increased oxygen demand.

The woodcutter’s actions have simple scientific explanations based on heat transfer and condensation. They are natural phenomena that anyone can observe, not acts of magic or ghosts.

Blowing on a hot cup of tea or soup is a common way to cool it. The moving air from your breath carries heat away from the liquid’s surface.

A stethoscope is a medical instrument that doctors use to listen to the sounds inside a person’s body, most commonly the heartbeat and breathing sounds in the lungs.

When air is heated, its molecules spread out, making it lighter or less dense than the surrounding cool air. This difference in density causes the hot air to rise.

The steady, rhythmic “thump-thump” of the heartbeat is often compared to the ticking of a clock, as both serve as a constant, internal measure of passing time.

Measuring the difference in chest size between inhaling and exhaling shows how much your lungs expand. This provides a simple way to demonstrate your lung capacity.