6. An iron nail is taken to the moon. Another is kept near the Gateway of India. While the
third is kept under Arabian sea. Compare the degree of rust formation on the three nails.
7. Why do the lengths of days vary throughout the year?
8. Why do you think our heart rate increases when we run?
9. Does a tsunami have a link with cyclones?
10. Why is a copper wire not used in the filament of a bulb or as a heating element of heater?
11. Why is chlorine called swimming pool chemical?
12. Why does our stomach grumble when we are hungry?
13. From which of the blood vessels is blood drawn during blood transfusion? Why?
14. Why do we urinate more frequently in winter than in summer?
15. Does the water table all around the Earth have a similar amount of water? Why?
16. Goat's milk is much easier to digest? Why?
17. Why do we get instant energy from glucose?
18. One litre of water at 40°C is mixed with one litre of water at 60°C. What will be the
temperature of the mixture?
19. Why do we often sneeze when we inhale a lot of dust-laden air?
20. Why should we not put stainless steel spoons in pickle jars?
Answers
Answer:
6) it will rust due to the moisture
7) The duration of day and night differs through the year because of the axis of the Earth. The Earth is tilted at an angle of 23.4°. Owing to this reason, the daylight is higher in summers than that in winters, and hence the difference in the duration of days and nights.
8) The heart must beat faster during exercise because by increasing the heart rate, the body is able to increase cardiac output and deliver the necessary blood flow to the muscles. Your heart is a muscle, and gets a workout during exercise. Its job is to get more blood out to the body's muscles when they work hard.
9) No, tsunamis and cyclones are not linked to each other. Cyclone occurs on the surface of water whereas tsunamis occur due to an earthquake or other underwater agitations.
10) No, copper wire cannot be used to make the filament of an electric bulb as copper wire has very low resistance. Therefore, the bulb will not glow if current is passed. It would also melt - the filament has to be white-hot to be any use.
11) Chlorine is added to the water to kill germs. When it is added to a swimming pool, it forms a weak acid called hypochlorous acid that kills bacteria like salmonella and E. coli, as well as germs that cause viruses such as diarrhea and swimmer's ear.
12) Growling is more commonly associated with hunger because it is typically louder when the stomach and intestines are empty and so the organs' contents don't muffle the noise. The physiological origin of this rumbling involves muscular activity in the stomach and small intestines
13) For blood sampling, blood is taken from veins and not arteries because: Arteries, on the other hand, are a tad bit deeper. The walls of veins are thinner than arteries'. The blood pressure in veins is less than that in arteries.
14) When that happens, your blood pressure will rise, because the same volume of blood is flowing through less space in your body. In response, your kidneys will pull out excess fluid to reduce your blood pressure, making you have to pee.
15) The soil surface above the water table is called the unsaturated zone, where both oxygen and water fill the spaces between sediments. The water table level can vary in different areas and even within the same area. Fluctuations in the water table level are caused by changes in precipitation between seasons and years.
16) Goat's milk has smaller fat globules as well as higher levels of medium chain fatty acids.This allows the body to digest the protein more smoothly and completely than when digesting cow's milk.
17) Carbohydrates, when consumed, have to be digested into glucose. As glucose can be easily absorbed in blood, it provides energy to the body. Hence, when glucose is directly taken, it does not have to be digested and thus acts as an instant source of energy
19) When we inhale air containing dust particles, the particles get trapped in the hair present in out nostrils. Sometimes, these particles may pass through the hair and enter the nasal cavity. Sneezing expels the foreign particles from the inhaled air and dust-free clean air enters our body.
20) If the pickles are salty the chlorine ions from the salt (sodium chloride) will start to etch the stainless steel causing it to pit. It is not a good idea to let anything with chlorine near stainless steel. Chlorine bleach will eat stainless steel. Muriatic acid is called hydrochloric acid and has a HCl formula. It eats stainless steel very nicely. Salty water put on the stove to boil will pit a stainless pot too.