Chemistry Unit 4 Review Answer Key: Fill & Download for Free

Being a Physics teacher, I am giving an exact analysis of Physics here.JEE Advanced 2018 was a computer based test and this is the first time a pure online nature of test took place.It was astonishing to see that questions from some chapters were completely missing. The missing topics were -Simple Harmonic MotionWaves (Transverse)Wave OpticsAlternating CurrentCircuit TheoryThe paper also saw a switch from very tough questions to easy and moderate level questions.Questions from Rotational Dynamics have always been a nightmare for students while this year the questions were really easy and concept based.There were questions from Electrostatics and Magnetism and the questions were of a moderate level again.No question from meter Bridge or potentiometer were asked while a basic formula based question was asked from Galvanometer conversion into ammeter.Units, Dimensions and Errors took a 12 marks part in the test (that's free marks for everyone I suppose).It is a rare event to see that questions from class 11th syllabus formed 61 percent (22 questions) of the paper while 12th syllabus formed the rest 39 percent (14 questions).Students who skipped their class 11th were in a catch due to this.11th syllabus carried 70 marks while 12th carried the rest 50 marks.The paper can be taken into easy to moderate level exam. Most of the questions could be seen in class examples and sheets.No question comes under the bonus category this time which is a huge improvement from the past years.Mathematics and Chemistry made things tough for the students. While Mathematics was on the lengthy side, chemistry was tricky, calculative and had mixed topic questions. Some might agree with me in saying that chemistry was one of the toughest in JEE in many years.Cutoff may be expected around 35 percent of the total marks which is 126 or a range between 120 to 140 marks.A good IIT is waiting for you in case you cross 190 or so marks.The above prediction is just an approximation. Others may not agree and these may not at all match with the real situations.Here is the answer key for you to match your questions. You can find the question paper and video solutions as well on coaching websites and you tube.P.S. Good luck and hope for the best. Inbox me your marks or for any other help. I will surely try to get in touch asap.

The origin of life is a huge unsolved problem. It won’t be completely solved in the next decade but aspects of the problem look solvable.This answer could be hard for people who haven’t taken a course in Biochemistry.Anyone who has looked casually at the field could easily get the impression that the problem is mostly solved. Look at this diagram from two of the best scientists in the field, Koonin and Martin.[1][1][1][1] It describes how life could have originated from undersea alkaline hydrothermal vents. The chart is detailed, comprehensive, specific, and scientifically plausible.There’s just one flaw in it. Nearly every step is purely hypothetical, lacking in empirical support. Nobody knows whether any of these steps actually occurred or even whether they can happen as described.[2][2][2][2]One of the authors of that chart, Koonin, isn’t very confident about that concept. He coauthored a paper describing an entirely different, incompatible, theory.[3][3][3][3]But this doesn’t mean that progress is impossible. There is one bit that’s widely accepted and has a firm scientific foundation. It’s called the RNA World. At some point, there were organisms that used RNA instead of DNA as their genetic material. The evidence for that rests on the following facts:Key portions of the genetic machinery in modern cells rely on RNA.[4]RNA strands are able to catalyze some of the reactions that are necessary for life.[5]Components of RNA, like ATP, are used by many biochemical pathways in most organisms.Some modern organisms, viroids, resemble hypothetical RNA world organisms. They use RNA as their genetic material and lack protein-coding genes.[6]Unsolved RNA World problemsWhere did the RNA nucleotides and nucleosides come from? There is no known nonbiological process which produces both the pyrimidine and purine ribonucleotides in reasonable amounts.[7] Some scientists are optimistic about solving this problem.[8]What was the catalyst for RNA replication? Without that, you can’t have reproduction or evolution. It could have been an RNA ribozyme that no one has discovered yet. Or it could have been inorganic chemicals that are naturally present.[9]How did RNA organisms activate nucleosides into nucleotides? Modern living forms must activate nucleotides by adding phosphate before they can be used. Adenosine, for example, is converted to ATP by adding three phosphate groups. It takes energy to add them but they allow RNA to be created from individual units. Nobody knows how an RNA organism might have done that.How did life evolve right-handed RNA? Modern biochemical machinery requires the correct enantiomeric forms of RNA nucleotides but abiotic processes produce both left- and right-handed versions.[10] One possibility is that some natural process separated out right- and left-handed versions of nucleotides. Another possibility is that primitive enzymes or ribozymes could work with both left- and right-handed forms.[11]How did RNA organisms evolve the ability to create and use proteins? Modern organisms use a very complicated system in which transfer RNA brings amino acids to ribosomes so they can be added to a protein chain. The exact amino acid to be used is defined by a complex genetic code. Koonin describes some possible evolutionary pathways in his book, The Logic of Chance.[12]How did the RNA World transform into the modern DNA world?Evolution requires a sequence of individual steps but there aren’t any obvious small steps when switching from RNA to DNA. The DNA replication machinery is different in the two main branches of life, archaea and bacteria.[13] That suggests that the common ancestor of those two branches might have been an RNA organism.General unsolved problemsWhere did life originate? That matters because each location provides different chemistry. Some investigators think it arose in undersea alkaline vents as shown in the first chart of this answer.[14] [15][16] But other investigators have raised serious objections to that idea.[17] Life could have arisen in anoxic geothermal fields. [18][19] Alternatively, Szostak proposed that life began in small ponds.[20]What sort of container did the earliest biochemical systems live in? Living things must be enclosed somehow. This chart lists some possibilities: among ice crystals, pores in rocks, within a droplet of water within oil, or within a membrane consisting of fatty acids.[21]What happened before RNA appeared? There are lots of proposals for self-replicating entities that existed before RNA. Nick Lane proposed that micells might appear on the edges of hydrothermal vents. These might have the ability to grow and split into new micells producing a sort of non-biological self-replicating entity. [22][23] Here’s a picture of one.What did the first organisms and their ancestors eat? You can’t have life without a source of energy. Martin and Lane proposed that biochemical systems used the pH difference between the inside and outside of pore in a hydrothermal vent as shown in this diagram.[24] But that wouldn’t work if life originated somewhere else. Early biochemical systems could have used UV light or maybe simply eat the biochemicals in the primordial soup. Later on, it may have used Hydrogen to convert CO2 to methane and acetate, if Hydrogen was available.[25]How did the molecular machinery in the first cells arise? Here are the structures of the two kinds of ATPase. [26] These structures, or something like them, must have existed in the very first cells. Nobody has any idea as to how they evolved.OddsHow likely is life to arise a planet having the right conditions? Is it so certain that living things will appear on every planet that resembles Earth? Or is there a big element of chance involved? Koonin discussed the possibility that life might be very rare. He computed that the probability of the DNA to protein translation and replication machinery might occur by chance in the observable universe is less than 10^–1,018.[27] That would mean that nearly all universes have no life at all. He suspects that there are many universes, so we just happen to live in one of the lucky ones. (You may have noticed that Koonin has proposed other theories that make life more certain.)More to readThere’s a lot more to know but this answer is already too long. This article does a first-rate job of defining major unsolved issues.http://n.ethz.ch/~nbennett/download/Reading_NEW/Catalytic%20RNA/Joyce.pdfFootnotes[1] https://www.molevol.hhu.de/fileadmin/redaktion/Fakultaeten/Mathematisch-Naturwissenschaftliche_Fakultaet/Biologie/Institute/Molekulare_Evolution/Dokumente/135.pdf[1] https://www.molevol.hhu.de/fileadmin/redaktion/Fakultaeten/Mathematisch-Naturwissenschaftliche_Fakultaet/Biologie/Institute/Molekulare_Evolution/Dokumente/135.pdf[1] https://www.molevol.hhu.de/fileadmin/redaktion/Fakultaeten/Mathematisch-Naturwissenschaftliche_Fakultaet/Biologie/Institute/Molekulare_Evolution/Dokumente/135.pdf[1] https://www.molevol.hhu.de/fileadmin/redaktion/Fakultaeten/Mathematisch-Naturwissenschaftliche_Fakultaet/Biologie/Institute/Molekulare_Evolution/Dokumente/135.pdf[2] Ancient Living Organisms Escaping from, or Imprisoned in, the Vents?[2] Ancient Living Organisms Escaping from, or Imprisoned in, the Vents?[2] Ancient Living Organisms Escaping from, or Imprisoned in, the Vents?[2] Ancient Living Organisms Escaping from, or Imprisoned in, the Vents?[3] Origin of first cells at terrestrial, anoxic geothermal fields[3] Origin of first cells at terrestrial, anoxic geothermal fields[3] Origin of first cells at terrestrial, anoxic geothermal fields[3] Origin of first cells at terrestrial, anoxic geothermal fields[4] The Ancestor Within: Michael Yarus: 9780674060715: Amazon.com: Books[5] The RNA world hypothesis: the worst theory of the early evolution of life (except for all the others)a[6] https://www.researchgate.net/profile/Santiago_Elena/publication/263741076_Viroids_Survivors_from_the_RNA_World/links/543bb1ec0cf2d6698be31328/Viroids-Survivors-from-the-RNA-World.pdf[7] Origins of building blocks of life: A review[8] Researchers may have solved origin-of-life conundrum[9] The eightfold path to non-enzymatic RNA replication[10] Chiral Key Found to Origin of Life | Quanta Magazine[11] A cross-chiral RNA polymerase ribozyme[12] Medicine & Health Science Books @ Amazon.com[13] DNA Replication in the Archaea[14] https://www.molevol.hhu.de/fileadmin/redaktion/Fakultaeten/Mathematisch-Naturwissenschaftliche_Fakultaet/Biologie/Institute/Molekulare_Evolution/Dokumente/135.pdf[15] Extreme accumulation of nucleotides in simulated hydrothermal pore systems[16] Proton gradients at the origin of life - Lane - 2017 - BioEssays - Wiley Online Library[17] Ancient Living Organisms Escaping from, or Imprisoned in, the Vents?[18] Open Questions on the Origin of Life at Anoxic Geothermal Fields[19] Origin of first cells at terrestrial, anoxic geothermal fields[20] https://www.scientificamerican.com/article/how-did-life-begin1/?redirect=1[21] https://scholar.google.com/scholar_url?url=https://www.researchgate.net/profile/Philipp_Holliger/publication/315052808_Nucleic_acids_Function_and_potential_for_abiogenesis/links/5af15ca5458515c283754b67/Nucleic-acids-Function-and-potential-for-abiogenesis.pdf&hl=en&sa=T&oi=gsb-gga&ct=res&cd=0&d=11395180778409664887&ei=KQ8IXYygKonemQHCs4o4&scisig=AAGBfm0lj9GdueACLdoKcTbEI9aNvHaj8Q[22] https://scholar.google.com/scholar_url?url=https://link.springer.com/article/10.1186/1759-2208-3-2&hl=en&sa=T&oi=gsb-gga&ct=res&cd=0&d=18256795192388354411&ei=QxEIXfSlKMGomQHH367YCw&scisig=AAGBfm3oLtoAxiapSLl7aY9ydPWGOYVRtA[23] https://royalsocietypublishing.org/doi/pdf/10.1098/rstb.2016.0419[24] http://nick-lane.net/wp-content/uploads/2016/12/LAM-BioEssays.pdf[25] The physiology and habitat of the last universal common ancestor[26] The mechanism of rotating proton pumping ATPases[27] Israel Ramirez's answer to What is an unpopular but plausible theory on abiogenesis?

Let's assume that you have prepared for NEET from class 11 and you have just few months left for final battle.First and foremost is AIM HIGHBelieve in yourselfEvery morning during 9–10 am make sure that you seat in a chair table and study uninterruptedly for 3 hours at a stretch without any break. This will simulate your D-Day exam time like situation.Make a fine line between expectation and reality. I mean until it is only you know best about your preparation, so don't expect beyond your limit and panic yourself.Don't lose the game. Always think that Now or Never. It is best to beat iron when it is hot. So always keep a positive mindset of cracking the exam this time.Now I am coming to study tips:First of all, this answer is for those who don't have an eidetic memory. Most of us have specific forgetting curve (Ebbinghaus effect). Below you can see a typical forgetting curveSo, Spaced Repetition is the only solution to this.Spaced Learning is a learning method in which highly condensed learning content is repeated after an interval.This forgetting curve is the main enemy for a pre medical aspirant. So deduce your own forgetting curve and revise and revise.Take strategy of 3R- Recap, Review, ReinforceInvest maximums time in eruditionDivide a topic to be revised into parts, get organized, set goals and prioritize topics to be reviewed4. stop procrastinatingYou may find study load to be dauntingly heavy, intimidating and disorganized, soIncorporate all your class note in preliminary reading note ( include book, lecture handouts)Structure your knowledge and prioritizeuse abbreviations, Mnemonics (visual and verbal). Make mnemonics using dirty language, vernacular language, emotional connection( be aware of the similarities and don't confuse yourself)Start revising with your strong areas first. Make these topics to best from good.Be brutal about your weak points.Study in short bursts, not long marathons.Don't highlight everything ( don't Berger paint your book)Use flash cards for revisionWhile revising a topic always prioritize key areas, set time goalDay by day baggy study load becomes organized and manageable which is key to efficiency.Now some tips for solving numerals:Deconstruct a numericalDon't panic and rush through the problemorganize information (force, mass etc)sketch the scene ( meaningful organization and mental visualization)verify unitsUse the formula and verify your answersolve the mixed type of problemmake a list of all formulas and see them every dayLearn how these formulas are deduced don't cramImplementation of the formula is the real hurdle for any numericalTips for studying biology and inorganic and organic chemistryAfter learning any make topic make sure that you are able to express it in your own wordswhile revising every time set a time span and complete that topic within that time. The next time you revise consequently reduce that time span. This will increase your revising ability which will be very essential a week before D-Day.Don't fall prey to Information Anxiety (especially in biology)Read NCERT as mother book and one or two reference books.Read-only relevant topics which are in ncert there is no need for extra learning in NEET because most students make mistakes in common questions.Take 5–10 years of question Bank and solve mcqs after you revise every topicEverytime you solve McQ compare yourself with earlier performanceEnroll for Full syllabus Mock test in AKaSH AND ALLENAppear in every test whatever be your preparation and compare yourselfThere is no place of rote learning in entrance exams so don't cram formulasSome general tips:Take power napsexercise regularly to reduce stressstudy smart not harduse punch word to revisesleep for at least 7 hours dailyLastly revise - solve mcq - give mock test - revise - solve mcq - give test and repeat this…Please upvote me, follow me for more tips regarding Neet preparation.Feel free to drop a comment.Thank you.