Q. & A.s ‑‑‑ SCIENCE
& TECH. – 5
So far I posted 146 Questions in my last SCIENCE
& TECH. Q. & A.s blog
posting. Now I start after that count.
147Q. Why molten wax which is transparent
becomes opaque at normal temperature?
Wax is a
substance containing mainly esters of higher fatty acids and long chain monohydric
alcohols. They are solid and crystalline
at room temperature.
They melt at
above 40oC without decomposition and remain transparent in the liquid state.
As they cool
down to room temperature, solidification begins and small irregular crystals
begin to form.
The surfaces of
these micro crystals scatter the light passing through them and make the layer
of wax lose its transparency.
148Q. Why is it difficult to cure common cold?
More than a
hundred viruses are said to be associated with common cold. The liust includes
Rhinovirus
[more than 100 types]
Corona virus [
4 types]
Influenza virus
[ 3 types] and
Adeno virus [47
types]
These symptoms
develop in 2 to 4 days.
Our body
develops immunity as nasal IgA and serum IgG antibodies to modify the illness
to give us relief.
149Q. What is a leap year?
The moon goes around the Earth once in 28 ¼ days. Every four years
this quarter day becomes a day. So every fourth year, month February contains
29 days. That is called leap year.
150Q. Why doesn’t the stomach digest itself?
1.
The surface of the stomach is always covered by a thick layer of
mucus secreted by the columnar cells lining its surface.
2.
The cells lining the stomach walls secrete about 1.5 litres of
gastric juice a day.
3.
The mucus lubricates food facilitating movement within the stomach.
4.
The mucus forms as a protective layer to stomach.
5.
The mucus is alkaline so neutralises the acidity of the gastric
juice
151Q. what is Heliocentric Theory?
Helio = sun
Helio centric theory means the
sun is the centre of solar system.
In this universe, the Earth is
nothing.
Gionardo Bruno proposed this and
the church burnt him alive.
Galileo proved this using his
telescope.
Copernicus further strengthened
this theory.
152Q. When a bulb breaks a loud sound comes. Why ?
Inside the bulb there is vacuum.
When it breaks, the air surrounding it rushes to occupy that place from all the
directions. That is why a loud sound is heard.
153Q. What is pulse polio vaccine?
It is a nation wide programme launched to
completely eradicate polio.
This is aimed at replacing the
virus causing the disease polio-myelitis with a vaccine virus.
This virus is a a low ebb during
December and January.
154Q. Why does hair turn grey?
Grey is merely the base colour of
hari.
Pigment cells are located at the
base of each hair follicle.
As a person grows older and older
pigment cells die and colour is lost from individual hairs.
155Q. How does an electric
line testor glow?
Bulb glows when AC from phase
passes to neutral.
In the case of tester our body
works as neutral or less potential.
That is why it glows.
156Q. why are umbrellas black?
Black body
is the best absorber of heat. As it absorbs heat coming from sun, we feel
cool under it.
157Q.
Does the Sun rotate?
Yes. Unlike earth, Sun has differential
rotation. That is all parts of the sun do not have the same period of
rotation. The rotation at its
equator is 26.9 days and at poles is
31.1 days.
The reason is a puzzle.
158Q.
why do we always see the same face of the Moon?
The Moon always presents the same face to us
because it period of rotation is the same as its period of revolution around
the earth.
159Q.
What is the difference between H-bomb and A- bomb?
A-bomb is nuclear fission and H-bomb is
nuclear fusion.
160Q.
April 1 is called fools day. Why?
In the beginning April 1st was considered as the new
year’s day. After 1564 it was changed to January 1st. Then onwards April 1st has become
fool day. It is because it has lost its prominence. But even 31st
March only all the accounts are closed. April 1st on wards new books
are opened.
161Q. Oil doesnot mix with water. Why?
Oil molecules are very long chains. Whereas
water molecules are very small.
Secondly oils have covalent bonds whereas
water has ionic compounds.
162Q. We
get sleep after heavy diet. Why?
The stomach walls have muscles. These muscles
have circular motion, oblique motion and oscillatory motion. For these
movements more blood is required. As a little quantity of blood goes to brain
and more to stomach we get sleep.
163Q.
Why all the eyes are not of same colour?
The colour of the eyes is decided by 46 genes.
It differs from being to being.
164Q. As
age increases the skin gets folds. Why?
It is because the skin loses its elasticity.
165Q.
Climbing up a hill is harder than climbing down. Why?
While climbing up we should work against
gravity to carry our body. There will be more stress on muscles, heart etc.
While climbing down we feel loss of weight.
In this gravity also helps.
166Q. Why
acids give burning sensation?
Acids of carbon compounds are non-dangerous.
There are some acids which are not harmful.
There are eight types of amino acids to save our life.
Acids of non-carbon compounds suck more water
and release heat.
When they fall on our body they suck water
from our body. This causes burning sensation.
167Q.
What is fool’s gold?
Iron pyrites.
It glows like gold. It contains 46% of ferrous
and 54% of Sulpher.
That is why it is called fool’s gold.
168Q. What is international date line?
180o longitude is called international date line.
Those who cross this line from west to east
add a day or vice versa.
169Q.
What is cinema scope?
The cinema films are of different sizes.
1.
8 mm
2.
9,5 mm
3.
16 mm
4.
35 mm
5.
70 mm
6.
Cinemascope
7.
Panavision
8.
Warner scope
9.
Super scope
170Q.
What are anti-freeze materials?
Salt, alcohol, ethylene glycol are the
substances which reduce the freezing point of water. That is why they are
called anti-freeze materials.
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