Some MCQs of Physics and Chemistry.

Q1)when the aircraft concorde is moving in horizontal plane at const speed 650 m/s its turning circle has radius of 80 km wat is ratio of centripetal force to the weight of air craft?
Ans.

Q2)when 0.24 gm of magnesium is reacted with excess HCl what volume of gas librated at RTP
Ans.

Q3)In mixture of NO and CO2 initialy containing 4 mol of NO and 0.9 mol of CO2 reaction ocur acording to NO+CO2>NO2+CO at eq 0.1 mol of CO2 was presnt what is Kc
Ans.

Q4)a box of mas m =6 kg slid with speed v=4 m/s acros frictionless flor it sudenly explodes into 2 pieces one piece with mass m1 =2kg moves in same direction with speed v1=8 m/s find velocity of 2nd piece
Ans. as momentum before collision= momentum after collision
for m2 ,m=m1+m2 6=2+m2 m2=4kg so 6(4)=2(8)+4(x) 8=4x x=2m/s

Q5)Q2) on groud the gravitational force on satelite is W wat is gravitational force on satelite when at height R/50 where R is radius of earth
Ans. On the ground, the distance (from the centre of the Earth) is R. In orbit, the distance is R+R/50 or (51/50)R. The force is (ETA: inversely) proportional to the square of the distance so the multiplier you want is (50/51)^2 ~=0.96W

Q6)equal weights of methane and hydrogen are mixed in an an empty container at 25 degre centegrad the fraction of total presure exerted by hydrogen is.
Ans. apply mole fraction formula by daltons law of partial pressure
as moles fraction=no of moles of components/no of total moles let no of moles H2= n/2 let no of moles of CH4=n/16 total moles = n/2 + n/16 =9n/16 so mole fraction of pressure exerted byH2= n/2 ÷ 9n/16 = n/2 × 16/9n =8/9 ans

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How to deal with Organic Reactions

How to learn the reactions of Organic Chemistry?
When one starts the Organic Chemistry in Second year, the first chapter that is the introduction is usually quiet easy to understand. The concepts are familiar to the one's we started reading about in the Organic Chemistry chapter from matric text book. How ever once the next chapters start, the concepts become too much to comprehend. Yes the physical properties, uses and structures are comprehensible but the chemical reactions are a bit too much.
With each successive chapter, the no of chemical reactions increases and it becomes confusing to remember what reacts with what to give you what. The alkanes, alkenes and alkynes all end up reacting with the same chemicals yet give varying products. here are some tips to make you understand the reactions in a better light:
Keep a pencil and paper with you while studying reactions. The more you right things down, the more they stay with you for ever.
Understand what is going on the reaction. This may seem tiresome but it is better to know where the electrons are going, how the bonds are being made and reformed again. So that if you forget the real equation, you can come up with it on your own using the chemical techniques which actually make the reaction happen.
This is also helpful in the Entry Test examination where the reactions may not be exactly like the ones given in the book. So if you know the mechanism of action, the organic chemistry multiple choice questions would be a piece of cake.
Make it visual. the more you make the reactions elaborate and colorful, the better. This is specially good when you are beginning Organic Chemistry. Once you get a hang of this, you wont be needing too much illustrations.
Also do lots and lots of practice on paper. The more you do that, the more it will stick in your brain. It is kind of like Mathematics in that way. Practice is the key.

How to Study Chemistry

How to Excel in Inorganic Chemistry

Inorganic Chemistry is the branch of Chemistry dealing with the study of inorganic compounds, their properties and reactions with other compounds. Students usually find it difficult to excel in this subject because of its theoretical and factual nature. Given below are some tips that will help you to better prepare for this subject.

1..Start creating interest in this subject. It is the best way to learn this(and obviously anything). Stop thinking that you have to read this only because you have to clear some exam or give some presentation. Learning this subject will undoubtedly help you in Organic and Physical Chemistry too as many concepts taught here are used in these fields too.

2..Collect your syllabus and prepare a lesson plan. This is highly important because this is really a vast subject and if you will go to learn everything you will probably get lost in the subject matter. Follow a good and recommended book covering your syllabus thoroughly. You can use Internet for your study too. It will give you numerous resources to search for the material and this way you will be able to gather more information but following a book will keep you concise and organised, a necessity in case you are preparing for an exam and have limited time.

3..Give regular and devoted time to this subject. Best time will be morning time. First of all, try to learn the Periodic Table. It is true that it is really a tedious task but you can skip f block elements in the initial stage. Some learn this by remembering the names of elements groupwise in some "song" form or some learn it by using the symbols of chemicals. It depends on you how you do it.

4..Study the properties of the elements by dividing your study material in groups acoording to the periodic table. Study the properties of individual elements by comparing withother elements in different groups. This will not only increase your interest in this subject but also help you to build a strong foundation for the topic: "Classification and Periodicity of Elements".

5..Learning chemical reactions will really help you. A good way to learn them is to understand the context in which these reactions are written. In books many reactions are written for a same element to illustrate its chemical properties. Once you have grasped the concept you will be able to write most of the reactions yourself. Always balance your reactions.Learning by writing is also a good practice.

6..Metallurgy is another important topic in this subject and needs greater attention as it contains many processes, elements' details and their applications. A mastery over this subject can be achieved if you understand the processes well instead of just cramming them. Try to reproduce the read things in written. Coordination Compounds is a comparatively easier and interesting chapter but requires good problem solving practice. You can refer to You tube or some other good video sites showing the processes and their application. This will help you to develop a firm grip over these topics.