Topic: Acid Base Indicators.
Why does a turmeric stain turn red?
No.
You got a stain on the shirt.
I know what you are thinking.
No, there is no point.
None of the two bottles are of any use.
Listen to me.
Don't wash the stain with the soapy solution.
The stain will turn red.
See, I told you.
Do you know why this happened?
This happened because the food which fell on the cloth had turmeric in it.
The color of turmeric is yellow.
It is a natural indicator which tells us whether a substance is an acid or a base.
Now, let us get back to those two bottles.
One contained lemon juice while one contained a soapy solution.
When we pour the lemon juice on the turmeric powder, we see that the color of turmeric powder is still yellow.
This is because lemon juice is an acid.
Turmeric does not change its color when it comes in contact with an acid.
Indicating that the lemon juice is an acid.
However, when we pour the soapy solution on the turmeric powder.
We see that the color of turmeric powder turns red.
This is because soap is a base.
When turmeric comes in contact with a base.
It changes its color from yellow to red, indicating that the soapy solution is a base.
That is why a turmeric stain turns red when it comes in contact with any kind of base.
Topic: Photosynthesis and Transpiration.
Why is the upper surface of a leaf more green and shiny than the lower surface?
Yes.
It is.
You don't believe me.
Why don't you check it?
The upper surface of a leaf is more green and shiny.
While, the lower surface is comparatively less green and shiny.
See, I told you.
Do you know why?
Ok.
Let me tell you.
You must be aware that chlorophyll.
Which helps the plant to prepare food, is responsible for the green color of the leaves.
But why is the upper surface more green than the lower surface?
This is because the upper surface of a leaf is more exposed to the sun as compared to the lower surface.
Hence, to trap maximum sunlight.
There is more chlorophyll on the upper surface as compared to the lower surface.
Hey.
You forgot.
You also wanted to know why is the upper surface of the leaf shinier, right?
It is due to the process called transpiration.
Transpiration is the loss of water from leaves, stems, etc. in the form of water vapor.
Now, to make sure that the plant does not lose a lot of water.
The leaves are covered with a shiny, waxy coating called a cuticle.
But being more exposed to the sun, the upper surface will tend to lose more water.
Therefore, the upper surface of the leaf is covered with a thicker cuticle as compared to the lower surface.
Hence, the upper surface of the leaf is shinier than the lower surface.
Topic: Light and Sound.
Why do we see lightning before thunder?
Don't go out tonight.
A huge storm is coming.
Look at the weather outside.
See, there's a huge lightning strike.
Now, very soon, you are going to hear some thunder.
I told you.
Don't get scared.
It's just thunder.
Do you know why you saw the lightning before you heard the thunder?
I will tell you.
An interesting fact is that lightning and thunder occur at the exact same time.
Then why do we see lightning first?
This is because light travels faster than sound.
The speed of light is 300 million meters per second while the speed of sound is only 340 meters per second.
Thus, the light from the lightning travels much faster to our eyes.
As a result, we first see the lightning, shortly followed by the sound of thunder.
Topic: Heat transfer.
Why do we use a black umbrella in summer?
Hey.
Looks like you are heading out today.
But it is so hot outside.
Why don't you take a dark colored umbrella, preferably black?
See, I warned you.
At least now use the black umbrella.
Now, do you notice the heat?
No, right?
Do you know why?
This is because in summer season, the temperatures are quite high.
Now, as compared to other colors, a black colored umbrella, being dark, absorbs most of the light.
Ultraviolet radiations coming from the sun and gets heated.
It then radiates the heat back into the air.
Thus, making a black umbrella, a good choice to use in summers.
Topic: Heat transfer.
Why are cloudy nights warmer than clear nights?
Hey.
Look at the weather outside.
It is too cloudy.
No.
Don't go near that bonfire.
It is going to be warm tonight.
You don't want to listen to me, right?
Alright. Go ahead.
Look.
I told you.
At least now will you listen to me.
During the day, our earth receives light from the sun and gets heated.
Now, during a clear night, that is, when there are no clouds.
This heat easily escapes through the atmosphere into space, resulting in cooling of the earth.
Now, to understand what happens on a cloudy night, let us heat the earth once again.
In this case, the clouds act like a blanket, preventing the heat from escaping into space.
Since the heat remains in the atmosphere, cloudy nights are warmer than clear nights.
Topic: Metals and Acids.
Why is curd not stored in copper containers?
Hey, wait. What are you doing?
Don't eat that curd.
It was stored in a copper container.
Please listen.
Fine, then bear the consequences.
I had warned you.
Do you know why this happened?
This happened because curd contains lactic acid in it.
When curd is stored in containers made up of metals like copper or brass.
The lactic acid present in it, reacts with the metal and forms metallic salts.
These metallic salts are harmful.
They make the curd unfit for human consumption.
Therefore, to prevent metals from reacting with acids present in food.
The metal containers are coated with a thin layer of tin.
Tin is also a metal.
However, it does not react with acids as rapidly as other metals do, thus keeping the food in the container safe.
Topic: Heat.
Why is a laboratory thermometer not used to check body temperature?
You have got fever.
Why don't you check your body temperature using a thermometer?
No.
Please don't use a laboratory thermometer.
You won't be able to get the correct reading.
Why don't you try another one?
This is called a Clinical thermometer.
A clinical thermometer is different from a laboratory thermometer.
Seems like you have made your choice.
A clinical thermometer has a kink.
When we check our body temperature, the kink present in it prevents the mercury from falling back down.
Thus helping the thermometer to hold the temperature recorded by it and giving us an accurate reading.
Now, in a laboratory thermometer, this kink is absent.
This is because a laboratory thermometer is meant to measure immediate temperature.
Hence, after recording our body temperature.
Until we check it, the mercury will fall, thus not giving us an accurate reading.
Topic: Turgor Pressure.
Why does a touch me not plant close?
Hey. Don't touch that plant.
You will get scared.
See, you did not listen to me.
Don't worry.
Nothing to be scared about.
Let me tell you more about this plant.
This plant is called the Mimosa Pudica plant.
Another name for it is 'Touch Me Not' Plant.
When anyone touches this plant, it closes its leaves with the help of pulvini.
Pulvini are present at the base of each leaflet.
They consist of cells filled with water.
This water applies pressure against the walls of the cells.
This pressure is called the turgor pressure.
It helps the leaflets to stand upright.
Now, when we touch a leaflet of the touch me not plant.
Specific parts of the plant release certain chemicals.
These chemicals cause the cells in the pulvini to lose water.
When water is lost, there is no more turgor pressure.
As a result, the cells collapse, resulting in the closing of leaflets.
Topic: Specific heat of water.
Why is water used in hot water bags?
Looks like your leg is hurting.
Use this hot water bag.
It will give you some warmth and provide you relief.
No. The bandage is not going to help.
See.
I told you.
At least now will you use this hot water bag?
You are feeling better, right?
Do you know how a hot water bag gave you warmth for such a long time?
This is due to a concept called specific heat.
Specific heat of a substance is the amount of heat energy absorbed or lost by that substance to change its temperature.
Now, the hot water bag consists of hot water.
As compared to other liquids like milk and acetone, the specific heat of water is much higher.
This means that as compared to others, water needs to absorb a large amount of heat to become hotter.
Now, did you know that water will take a long time to cool down as compared to milk and acetone?
Thus, water will take a longer time to become cool.
Hence, it proves to be very useful in hot water bags because the warmth can be utilized for a longer time.