Science bits Iron balls

SCIENCE & TECHNOLOGY BASED QUESTIONS

PHYSICS

Question: (1): An iron ball floats on mercury  but gets immersed in water. What is the reason?

Ans: If the density of the body (iron ball) is less than the density of given fluid (water), then the body (iron ball) floats on it (water).

Question : (2) Artificial satellites are always launched from the earth i.e. Sriharikoti in the eastward direction. What is the reason?

Ans: Due to eastward motion of earth’s rotation (earth rotates from West to East) a satellite projected in east direction is helped by this motion in achieving the escape velocity easily.

Question : (3) On cotton cloth, when water drops are sprinkled, they spread on the cloth? What is the reason?

Ans: Capillarity 

Note: Capillarity is the reason for the oil-lamp and cotton made stick.

Question (4):

The intensity of ‘Sound’ is measured in which units?

Ans: Decibel.   ‘Bel’  is the basic unit of the measurement of sound intensity.

Question (5) What is the noise level of a Supersonic plane ?

Ans: 120 decibels

Question: (6) The word LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. Who theoretically proved that the process of stimulated emission must exist?

Ans: Albert Einstein in 1917.

Question : (7) What are the characteristics of of Laser ?

Ans : The most striking features of a laser beam are

(i)           High monochromaticity

(ii)          High degree of coherence

(iii)         High directionality (i.e., less divergence)

(iv)         High brightness

Question : (8) How many types of Lasers are there?

Ans:  The following type Lasers are there:-

(i)           Solid state lasers

(ii)          Semiconductor lasers

(iii)         Gas lasers

(iv)         Liquid lasers

Question : (9): The first laser was constructed by whom in 1960?

Ans: T.H.Maiman . He employed a crystal ruby as the active medium.

Question (10): Now a days on almost all consumer items, bar codes are printed. How this bar code is read by bar code readers?

Ans: By Laser beam. When laser light scans the bar code label, the dark lines of the cod absorb light while the bright lines reflect light. This light modulation is registered by a photosensitive light detector. This information pases to the computer which inturn identifies the product and displays the price. Such bar codes are also used in libraries.

Question (11): What is Optical Fiber?

Ans: It is a very thin and flexible optical mediumhaving a cylindrical shape consisting of

(i)           The core

(ii)          The cladding and

(iii)         The outer jacket

Question: How light is propagated through optical fiber core?

Ans: Total internal reflection of light

Question : (12): What is Fullerence?

Ans: A fullerence is a molecule composed entirely of carbon, in the form of a hollow sphere, ellipsoid or tube. Spherical fullerences are also called buckyballs, and cylindrical one called carbon nanotubes or buckytubes. Fullerences are similar in structure to graphite, but they may contain pentagonal rings.

Question (13)  Which semiconductors are very widely used in the manufacturing of diodes and transistors?

Ans: Germanium and silicon

Question (14) : Give examples for Ferromagnetic materials?

Ans: Iron, Cobalt, Nickel, Gadolinium

Question (15) : What are the characteristics of a musical sound?

Ans:The three main characteristics of a musical sound  are

       (i)intensity or loudness, (ii) pitch or frequency and (iii) quality or timbre

CHEMISTRY

Question (1) Why hard water is not suitable for  drinking,  washing clothes with soap, use of boilers ,irrigating crops?

Ans: Hard water contains nitrates and chlorides

Question: ( 2 ) :

Where  Sodium metal is to be stored ?

Ans: under kerosene

If sodium is kept in air, it burns to form Na2  O  and Na2  O 2

Question : (3) :

 Galvanised iron sheets are protected from rusting due to the presence of a layer of which metal?    

Ans: Zinc

Question: (4) Synthetic detergents can leather well in which water?

Ans: Hard water  like Well water                                                                                                              

Question: (5)

Most of the explosions in mines occur, due to the mixing of                                                       

Ans:  methane gas  with air         

Question (6) Aspirin is known as

Ans: Acetyl salicylic acid

Question : (7) : Why DDT is banned ?

Ans: Non-biodegradable pollutant

Question (8): Aluminium is extracted by the electrolysis of _____

Ans : alumina mixed with molten cryolite

Question (9) : Cyanide process or Mac Arthur-Forest Cyanide process  is used for the extraction of ______

Ans : Silver

Question (10) : Regular use of Ammonium Sulphate as fertilizer in agriculture field, increases _____  of the soil ?

Ans : acidity

Question  (11) :  Glass is a _______

Ans : Super cooled liquid, which forms a non-crystalline solid. The common lime-soda glass used for bottles and jars is a supercooled mixture of sodium and calcium silicates.

Question : (12) : Graphite is a soft solid lubricant extremely difficult to melt. The reason for this anomalous behavior is _____________

Ans : Graphite has carbon atoms arranged in large plates (layers)  of rings of strongly bound carbon atoms with weak interpolate bonds

Question : (13) : Alum is  widely used to purity water since _______

Ans : it coagulates the mud particles

Question : (14) :  For making good quality mirrors, plates of float glass are used. These are obtained by floating molten glass over a liquid metal which does not solidify before glass. The metal used can be _____

Ans : Mercury

Explanation: Mercury solidifies after glass, so used for making good quality mirrors.

Question : (15) :  Chlorofluorocarbons are responsible for the depletion of which layer?

Ans : Ozone layer

SCIENCE & TECHNOLOGY QUESTIONS, BASED ON RECENT DEVELOPMENTS

Question(1): Indian Railways is providing a facility called as National Train Enquiry System   . What is the latest news?

Ans: A new mobile app and desktop app on Windows 8 platform for train enquiry is the recently added. It is  an enhancement to National Train Enquiry System (NTES) and it  has been developed by Centre for Railway Information Systems (CRIS), the IT wing of Indian Railways in consultation with and support from Microsoft. 

Question (2): In Aeroplanes, cell phones are allowed.  Cell phones should be kept in which mode?

Ans: Cell phones should be on flight/airplane mode.

The Directorate General Civil Aviation (DGCA) has amended its CAR Section 5 Series X Part I relating to air safety today and decided to allow the use of Portable Electronic Devices (PEDs) including cellphones. The use of PEDs shall be in the non-transmitting mode commonly called flight/airplane mode. The amended CAR also directs all operators for reporting of any suspected or confirmed PED interference or smoke or fire caused by PEDs to the DGCA. It also lays down the guidelines for the crew training. 

Question: (3)

IRNSS-1B satellite is successfully placed at 55 deg East longitude, collocated with IRNSS-1A and GSAT-8 satellites.  Where is 55 degrees East longitude, used for this purpose?

Ans: It is the orbit, where IRNSS-IB satellite is travelling

Question: (4)  Fifth orbit raising operation of IRNSS-1B is successfully completed by firing Apogee Motor for 134.4 seconds in morning. The expected orbital parameters are: Perigee Altitude: 35328 km, Apogee Altitude: 35931 km, Inclination: 30.9 deg. What is Apogee?

Ans: Apogee is the nearest point from Earth, it the orbit of the IRNSS – 1B satellite

Question: (5) Mars Orbiter Spacecraft was launched onboard PSLV-C25 on November 05, 2013. On December 01, 2013, Trans Mars Injection manoeuvre was conducted successfully and the Spacecraft was set in its course towards Planet Mars through a helio-centric trajectory.  What is ‘helio-centric trajectory?’

Ans: The path of the rocket or any projectile is called as trajectory. Helio-centric means, the spacecraft is revolving around the Sun, just like Earth, Venus, Mars, etc. Earlier, the spacecraft is revolving around the Earth because it is in the sphere of gravitational pull of earth.

Question: (6)

The Indigenous Cryogenic Upper Stage was successfully flight-tested onboard GSLV-D5 launch vehicle on January 05, 2014 from Satish Dhawan Space Centre SHAR, Sriharikota. What is used in the Cryogenic engine?

Ans: Liquid Hydrogen as fuel and Liquid Oxygen as oxidizer.

Question : (7)
After a flight of 17 minutes 5 seconds, GSAT-14 satellite was precisely injected into a Geosynchronous Transfer Orbit with a Perigee (nearest point to Earth) of 175 km and an Apogee (farthest point to Earth) of 35,945 km with an orbital inclination of 19.3 degree with respect to the equator. 

Geosynchronous Transfer Orbit is  which  type of  orbit ?

Ans: It is an elliptical orbit it is an elongated orbit.  It is not perfect circle.

Question: (8) : Why Indian scientists are preferring nuclear power plants from the point of  air pollution?

Ans: Nuclear power plants produce practically no carbon dioxide (CO,), sulphur dioxide (SO,) or nitrogen oxide (NOx) thus avoiding greenhouse emissions. Nuclear power, as a safe, environmentally benign and economically viable source of electricity, can meet the increasing electricity need of the country.

Question: (9)

DRDO has developed a state-of-the art technology for the production of titanium sponge. What are the benefits of Titanium?

Ans:It is the principal raw material for the manufacture of Titanium alloys for aerospace and various corrosion resistance applications.