Chemistry of life:

1. What is organic chemistry?
2. What is DNA?
3. What is the carbon cycle?
4. What is a carbon chain?
5. The ‘ropes’ of the DNA molecule are altering groups of chemicals called sugars and phosphates. True/False?

Nuclear power:

1. Who invented the atomic bomb?
2. How can radioactivity be used to indicate age?
3. What is an atomic bomb?
4. What is half-life?
5. What is radioactivity?

Light:

1. How do things absorb light?
2. What happens at an interference fringe?
3. What are photons?
4. Does light travel in waves?
5. Why is the sky blue ?

Answers

Chemistry of life

1. The chemistry of carbon and its compounds is known as organic chemistry. Carbon’s unique atom structure means it links atoms together in long chains, rings and other shapes to form thousands of different compounds. These include complex molecules, such as DNA, that are the basis of life.

2. DNA stands for deoxyribonucleic acid. It is the amazing long double-spiral molecule found inside every living cell. It is made up of long chains of sugars and phosphates linked by pairs of chemical ‘bases’-adenine, cytosine, guanine and thymine. The order in which there bases recur provides in code form, the instructions for all the cell’s activities, and for the lifespan of the entire organism.

3. The carbon cycle depends on animals and plants. The carbon cycle circulates like this: animals breathe out carbon as carbon dioxide. Plants take in carbon dioxide from the air and convert it into carbohydrates. When animals eat plants, they take in carbon again. And the cycle goes on.

4. The linking of carbon atoms together (like in a chain) to form very long thin molecules is called a carbon chain.

5. True.

Nuclear power:

1. The first atomic bombs were developed in the USA towards the end of World War II by a team of scientists under the leadership of Robert Oppenheimer (1904-1967).

2. Radioactivity proceeds at a very steady rate. So, by measuring how much of a substance has decayed radioactivity, you can tell how old it is. With once-living things, the best radioactive isotope to measure is carbon-14. This form of dating is called carbon dating.

3. One of two main kinds of nuclear weapon is the A-bomb or atomic bomb. It relies on the explosive nuclear fission of uranium-235 or plutonium 239.

4. Scientists cannot predict when exactly an atomic nucleus will decay. But they can predict how long it will take for half the atom in a given quantity of a radioactive element to decay. This is its half-life. Strontium-90 has a half-life of 9 minutes. Uranium-238 has a half-life of 4.5 billion years.

5. The atoms of an element may come in several different forms or isotopes. Each form has a different number of neutrons in the nucleus, indicated in the name as in carbon-12 and carbon-14. The nuclei of some of these isotopes the ones scientists call radio isotopes – are unstable, and they decay (break up) releasing radiation comprising streams of particles called alpha, beta and gamma rays. This is what radioactivity is.

Light:

1. When light rays hit a surface, some of it bounce off and others are absorbed by atoms in the surface, warming it up very slightly. Each kind of atom absorbs particular wave lengths (colours) of light. The colour of the surface depends on which wavelengths of light are absorbed and which reflected.

2. Interference is what happens when two light waves meet each other. If the waves are in step with each other, they reinforce each other. This is known as positive interference and you see bright light. However, if they are out of step, they may cancel each other out and this is called negative interference where you only see shadows. Interference fringes are bands of light and shade created by altering positive and negative interferences.

3. Protons are almost infinitesimally small particles of light. They have no mass and there are billions of them in a single beam of light.

4. In the last century scientists believed light travelled in tiny waves rather than bullet-like particles. Now, they agree it can be both.

5. Sunlight is white, which means it contains all the colours of the rainbow. The sky is blue because air molecules scatter – reflect in all direction – more blue from sunlight towards our eyes than any other colour.

Win a valuable book from Books.lk

“Reading maketh a full man,” it is said and the importance of reading need not be reiterated. And, it is with the objective of promoting the habit of reading among children that the Junior Observer in collaboration with Bookazone (Pvt.) Ltd; the innovators of the country’s first web portal (www.books.lk), launched a competition in September.

We give a lucky reader an opportunity to win a valuable book priced at Rs 1000 from books.lk. All you have to do is answer a the question and mail it to the address given, on or before Friday of that week.

The name of each week’s winner will be published later.

Here is how Bookazone will help you enter the magical world of books, to not only entertain yourself but also enhance your knowledge.It allows you to purchase any title of book regardless of the author, publisher, or the country of origin. Although Bookazone web portal was limited to English users since 2009, the latest additions of Sinhala and Tamil is also accessible on www.poth.lk and www.puththagam.lk listing a wide range of books written and published in local languages in addition to what is offered in English apart from magazines, CDs and DVDs. Once you place an order at Bookazone and make your payment,the deliveries are made free of charge using the best secured mode to any part of the island. In case you don’t see the title listed in the Bookazone web portal a simple email can be sent to inquire the availability, price, and the number of days that it will take to source the book.So, keep improving your general knowledge to answer the question posed every week. And what better way to do so than by READING!

Winner of coupon No 6 is :
Shamal Kumaratunga
14/A, Jaela Watte
Andiambalama