Q. & A.s SCIENCE & TECH. – 7

Q. &  A.s  ‑‑‑  SCIENCE  & TECH. – 7

196Q. Why dogs always keep tongue out?

Through tongue the water gets evaporated and the body temperature is maintained. Why because dogs do not have seat pores or no sweating.

197Q. Why appendix is not developed in human beings?

In ruminating animals, carnivorous animals, appendix too participates in digestion process. The secretions are also helpful in digestion process.  Human beings eat cooked food. So the use of appendix is nonoperational.

198Q. Why do we get cold in winter?

Virus develops at 32^oC. Our body is at about 37^oC. As we remain in door because of poor ventillation the temperature inside nose comes to 32^oC. This temperature becomes host to virus. UV rays kill virus. But as the sun’s heat is less, less germs are killed.

199Q. How do birds fly?

Their muscles are strong and their bones are light. Their bones are light with spaces full of air.

Beating flight at the time of rising in sky or landing.

Gliding flight when they are carried away by current of air.

200Q. What happens when we are afraid?

The brain releases a hormone called adrenalin.

This increases the glucose content in the blood so that the muscles are given extra energy.

This adrenalin increases that heart beat and quickness of breath.

201Q. Why doesn’t earth cool itself?

The radio active rays released from the core of the earth release a lot of energy. Due to this the earth does not cool itself.

Secondly the amount of heat that it receives from the sun is more than what it loses.

202Q. Why sometimes heart beat is faster?

The movements of muscles create carbonic acid. It reaches the heart in 10 seconds. If more carbonic acid reaches the heart, the heart beats faster.

1.      The other reasons are

2.      When there is excitement,

3.      When we get fever

4.      When we are afraid,

The heart beats faster.

1.      The heart beats slow

2.      When we are depressed,

3.      When we sleep,.

203Q. Why there are 7 days in a week?

The number of days in a week differs from culture to culture.

West Africa     4 days.

China/Europe  5 days

Old calendars  6 days

Egypt              10 days

Secondly in those days only 7 planets were known.

The names of a week are given by Babylonians.

204Q. What imparts fragrance to flowers, fruits and spices?

It is due to  oils present in them.

Those oils are soluble in alcohol, ether, vegetable mineral oils.

These oils may be grouped as alcohols, esters, aldehydes, ketones, lactones oxides.

Oils are made in leaves but as plant grows they are transported to different parts of plant.

The main purpose is not known.

205Q. FPS to MKS.

1 pound           = 453 gms

1 stone            = 6.35 kgs

1 Newton        = 102 gms

1 ounce            = 28 gms

1 carat                         = .0002 kgs     = .2 gms

1 dram             = 1.77 gms

1 grain             = .065 gms

206Q. Positive Place values. Above zero.

Deca                            10¹

Hector                         10²

Kilo                 K         10³

Mega               M         10⁶

Giga                G         10⁹

Tera                 T          10¹²

Peta                 P          10¹⁵

Exa                  E          10¹⁸

Zetta                Z          10²¹

Yotta               Y         10²⁴

207Q. Negative place values. Below zero.

Deci                             10^-1

Centi                           10^-2

Milli                 m         10^-3

Micro                           10^-6

Nano               n          10^-9

Pico                 p          10^-12

Femto              f           10^-15

Atto                 a          10^-18

Zepto               z          10^-21

Yocto              y          10^-24

208Q. what are cosmic rays?

Cosmic rays are electromagnetic rays of very short wave length. These rays come from other stars.

209Q. what is anti matter?

For every particle of micro world there is anti particle.

Electron           x          anti-electron

Proton             x          anti-proton

Neutron           x          anti-neutron

And so on.

Matter consisting of anti-protons in the nucleus and anti-electrons going around it is called anti-matter.

210Q. How is the age of fossils measured?

Radioactive isotope of carbon is 146C. Its half life period is 5730 years. When  a fossil is found, the amount of carbon present in it indicates the life of the fossil.

If the life of the fossil is greater than thousands of years, other isotopes of radioactive radium or some other materials are used.

211Q. How is the height of a mountain measured?

Using triangulation method, using goniometer the height is measured.

Today we have lasers to accurately measure the heights.

212Q. How is the depth of the ocean measured?

Using SONAR [sound navigation and ranging]

This equipment is fitted at the bottom of the ship. It generates Ultrasonic waves. These waves travel to the depth, touch the bottom, reflect back and create a sound in the set. We know the speed of the Ultrasonic waves, the time can be recorded using stop clock and the distance can be calculated.

V = d/t

D = Vxt

If we half of it vxt/2 gives the depth of the ocean.

213Q. There is a peculiar smell after rain. Why?

Streptomycetes are the bacteria in the soil. It releases certain volatile chemical compounds. They release compounds such as geosmin and 2 methyl isoborneol  when wetted by rain water after a long dry spell. This odour is only after the first rain of the rainy season.

214Q. Why there is ice on the Himalayas?

In troposphere as we go up for every 1 km height 6.4^oC temperature is decreased. 6100 metres is called the ice line. Above this line we can see the formation of ice.

215Q. why do stars twinkle?

Light passes through layers of atmosphere having different temperatures. Light has a property called interference. That is why we see the stars twinkle. Actually they won’t.

215Q. water is colourless.  Then why water fall is white?

Water while falling from a height breaks into drops, gaps, etc. The light falling on those fragments reflects. That is why it seems white.

216Q. let water be poured in any container  or on land having pits has the surface straight. Why?

It is due to surface tension.

217Q. Why mercury drops are spherical?

Mercury has the highest surface tension. That is why each drop seems to be perfect sphere.

218Q. what are terminator seeds.

These are give crop only once. The seeds of these crops won’t give plants. That means after one generation they won’t work like seed.

They are good for only consumption.

219Q. why does sun flower always face the sun?

The sun flower has auxin hormone present in the stem. It exhibits phototropism. Due to this it always faces the sun.

220Q. Does the Sun rotate?

Yes. Unlike the earth, sun has differential rotations. That is all parts of the sun donot have the same period of rotation. The rotation time at its equator  is 26.9 days and at pole 31.1 days. The reason is a puzzle.

           

           

Q. & A.s SCIENCE & TECH. – 6

Q. &  A.s  ‑‑‑  SCIENCE  & TECH. – 6

171Q. What is China clay?

This white clay was first utilised by the Chinese to make earthen ware.

That is why it is called China clay.

It contains

46%     Silica

40%     Alumina Al₂O₃

14%     water.

172Q. What is acupuncture?

2500 years ago it was first used in China.

According to this system there are 787 points in human body from where body can be controlled.

Very thin long needles are pricked into these points depending on the disease.

Each disease will have its own points to be pricked.

How it functions? So far no body knows.

173Q.  What is supersonic speed?

The speeds of those objects which travel faster than sound i.e., >1200 kmph is called super sonic speed.

Eg.,  concorde,  stealth

174Q. What is catalyst?

Catalyst is  a substance which promotes the reaction without participating itself.

These are of three types.

1.       Positive catalyst :- this increases the rate of reaction.

2.       Negative catalyst :- this reduces the rate of reaction.

3.       Auto catalyst :- Mn⁺²

Catalysts are essential for plastics, rubber, gasoline, fats, H₂SO₄, NH₃ …preparations.

Enzymes are catalysts to digest food in our body.

175Q. what is escape velocity?

The velocity required to an object to get out of the gravitational attraction of the Earth.

Eg., for Earth it is 11.2 kmps.

176Q. In whatever way we throw seeds, plants come up and roots go down. Why?

The Earth rotates at 1600 kmph. There is created centrifugal force. The heavier objects are thrown out and the lighter ones are sucked in. The plant is heavier than the roots. That is why plants are thrown out and roots are sucked in.

177Q. Why are the rain clouds black?

These clouds are low, amorphous and occur at high altitudes. Cumulonimbuses are the main rain clouds. Above these clouds sun’s rays are reflected. That is why below they are black.

178Q. Why are concentric circles aof different radii sometimes seen around the moon?

It is mainly due to refraction of light that pass through the ice crystals.

179Q. When the sap of green mango falls on our body bubble appears. Why?

Nature has given a gift to the tree. This gift protects the nuts from enemy. The sap contains phenol.

180Q. What is the meaning of stones in kidneys?

Calcium oxalate, calcium phosphate chemicals solidify and form as stones.

“Laxalo bacter phamy “ is bacteria. It breaks these stones. For this purpose it produces some enzymes.

If these enzymes are artificially created and introduced in our body the stones melt.

181Q. Why doesn’t  blood clot?

For clotting of blood plateletes are required. These are called thrombocytes.

In 1 cu.mm the count will be 1,50,000 to 3,50,000.

If their number decreases to less than 66,000 they won’t clot.

This disease is called purpura.

182Q. Some  tankers especially will have chains hanging in front of them. Why?

When the lorry travels at high speeds, there causes a friction between lorry and the road. The electrons lost by the road occupy the surface of the lorry. A spark may trigger at any time. To avoid this the chains are fixed hanging. When chains hit each other the electrons on the body get discharged.

183Q. What does an egg contain?

Egg contains 8 types of amino acids.

The vitamins are A, B, D and K.

There are 11 minerals.

Fat is 6%.

184Q. Eagles do not flap their wings often yet fly for long. How?

Eagles adopt an energy saving flight mode called gliding. Their broad wings and broad rounded tail enable them to exploit thermals in the air. For maximum time they glide.

185Q. What is the difference between petrol engine and diesel engine?

PETROL	DIESEL
1] the ignition of fuel is done by spark plug. 2] during intake stroke petrol and air mixture is simultaneously introduced. 3] here air is not required to be preheated. 4] the plug ignites the fuel air mixture.	1] no spark plug is used. 2] in the intake stage air is sucked in the cylinder where it is compressed to 1/16th of its original volume 3] in this process the temperature of air is considerably raised. 4] --

186Q. What is LPG ?

LPG stands for liquefied petroleum gas.

It is a mixture of butane and isobutene which has been liquefied by compressing.

It also contains in very little quantities of ethyl mercaptan.

Its source is crude oil.

187Q. What is water gas?

CO + H₂ .

The combination of these items is called water gas.

188Q. What is producer gas?

CO + N2.

The combination of these two is called producer gas.

189Q. What is coal gas?

It is a mixture of Hydrogen, methane, and carbon monoxide.

H₂                    = 45 – 48%

Methane          = 32 – 35%

CO                  = 8%

Acetylene        = 2%

Ethylene          = 3%

N₂                    = 4 – 8%

CO₂                 = 1%

190Q. What is coal tar?

It is a mixture of carbon compounds.

They ar benzene + xylene + toluene + phenol + napthalein + anthracene

191Q. What is the fuel used in rockets.

Methyl hydrazine        CH₃NHNH₂   

            +

Dinitrogen tetra oxide N₂O₄

192Q. Why doen’t match stick catch fire of its own?

It is because the ignition temperature of match stick is higher than the room temperature.

193Q. What is the difference between a bomb and a reactor?

Whatever energy is there in the material is taken out at a time it is called bomb.

If the energy is taken out in installments for a long time it is called reactor.

194Q. How are proteins consumed by our body?

Proteins are digested by proteolytic enzymes. They are converted into amino acids.

195Q. What are the major components of food?

1.      Proteins

2.      Fats

3.      Carbohydrates

4.      Minerals

5.      Vitamins

6.      Water  and

7.      Roughage.