goIIT: IIT JEE AIEEE CET WBJEE VITJEE BITSAT IIIT AICET Engineering Entrance Experts, Student Discussion Community, IIT JEE Preparation Online

a)-(p),(t)

KE of a system is conserved in elastic collision. When there is no net external force, the KE needn't be conserved as internal forces can do work & change KE. It is constant in uniform circular motion but in the case of isolated system of large bodies, since the bodies are large we must consider gravitational force btw them which can change kinetic energy.

(b)-q,s

In inelastic collision, kinetic energy of the system is not conserved. In case of isolated system of large bodies, the kinetic energy will change due to the gravitational force which is an internal force.

(c)-p,q,r,s

Linear momentum is conserved whenever there is no net external force, irrespective of the type of collision.

(d)-s

Note that the option says "position" of centre of mass. When bodies are moving in elastic or inelastic colission centre of mass is moving and hence its position if not fixed. When there is no net external force, even then centre of mass can move with constant velocity and hence its position does not have to be fixed. In uniform circular motion, centre of mass does not necessary have a fixed positon.

9/10 for the beautiful mermaid pic....

gud try.......

If lone pair electrons are present on the central atom, these can occupy one or more of the sp3 orbitals. This causes the molecular geometry to be different from the coordination geometry, which remains tetrahedral.

In the ammonia molecule, for example, the nitrogen atom normally has three unpaired p electrons, but by mixing the 2s and 3p orbitals, we can create four sp3-hybrid orbitals just as in carbon. Three of these can form shared-electron bonds with hydrogen, resulting in ammonia, NH3. The fourth of the sp3 hybrid orbitals contains the two remaining outer-shell electrons of nitrogen which form a non-bonding lone pair. In acidic solutions these can coordinate with a hydrogen ion, forming the ammonium ion NH4+. Although no bonds are formed by the lone pair in NH3, these electrons do give rise to a charge cloud that takes up space just like any other orbital.

In the water molecule, the oxygen atom can form four sp3 orbitals. Two of these are occupied by the two lone pairs on the oxygen atom, while the other two are used for bonding. The observed H-O-H bond angle in water (104.5°) is less than the tetrahedral angle (109.5°); one explanation for this is that the non-bonding electrons tend to remain closer to the central atom and thus exert greater repulsion on the other orbitals, thus pushing the two bonding orbitals closer together.

hope u understood.....

gr88888 score... was it B Mat series????...keep going like this frend and u have a fair chance of getting into IIT...

The iodoform test or iodoform reaction is a qualitative chemical test for the detection of ketones and aldehydes carrying an alpha methyl group. The reagents are iodine and sodium hydroxide.

Only methyl ketones, or alcohols with the feature:

CH3CH(OH)-R
may undergo this reaction.

56 nd ........

Hi,

I hope this info will be useful....

The number of students taking this examination has increased substantially each year with the JEE-2006 registering about 300,000 candidates (the number of exam-takers in each of the previous five years was under 200,000). The number of seats available in total is about 5500, indicating a selectivity of about 1 in 50. The break-up of seats for 2005 and 2006 is:

Institute	Intake (2005)	Intake (2006)	Intake (2007)
IIT Bombay	574	574	574
IIT Delhi	553	553	553
IIT Guwahati	302	365	365
IIT Kanpur	555	555	541
IIT Kharagpur	779	895	874
IIT Madras	550	520	540
IIT Roorkee	577	616	746
Total (IIT's)	3890	4078
IT-BHU	643	708	686
ISM Dhanbad	402	658	658
TOTAL	4935	5444

****The age limit for appearing in IIT-JEE is 25 years. For candidates belonging to SC, ST and PD categories, the relaxed age limit is 30 years. Also, starting 2007, a candidate can take the JEE two times at the most. This has been done mainly to reduce stress on students and discourage the concept of "cram schools" ? where students are made to memorize all types of possible exam questions. Furthermore, from 2007 onwards, students who are selected for admission to an IIT cannot attempt the examination again in the future.

All d best for all IIT aspirants 2008......

xcellent!!

good job... thanx a lot buddy...

Many scientists think it is possible that there is life elsewhere in the Universe, but that finding it may prove difficult.

First of all, we don't know exactly what form life on other planets outside our solar system might take, so it is difficult to know how to search for it. Second, the universe is a big place, and radio signals (and space vehicles) travel too slowly to allow us to find life that is very far away.

We do know something about the conditions on Mars, the planet in our solar system which is most likely to have life, and it turns out to be similar to the conditions in Antarctica (except for the lack of oxygen).

So we can guess what forms of life might be able to survive there, and there are projects under way that will someday send machines to Mars which can look for these kinds of life.

yeah!! we need to look at this issue quite seriously.....

9/10 coz i am a gr8 fan of HP......

hmmmmm.....test....

the power of mind

Olny srmat poelpe can.

I cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid, aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn?t mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Amzanig huh? yaeh and I awlyas tghuhot slpeling was ipmorantt!

if you can raed tihs peslae rtae it !!
Olny srmat poelpe can.