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.