Concept of Chemistry
Knowledge-based Questions & Answers:
Ques-1. Which language is alchemy word from?
Ans. Alchemy is from Arabic “Al-chimia” word.
Ques-2. When did the use of color start?
Ans. The Indian civilization started using color to make clothes more attractive almost 5000 years ago.
Ques-3. What is ink?
Ans. Ink is a toxic carbon particle made by burning wood and coal.
Ques-4. What is organic compound?
Ans. The chemical compounds that have one or more carbon atom attached with other elements such as hydrogen, oxygen, nitrogen etc in covalent bonding, they are called organic compounds.
Ques-5. How do plants produce carbohydrates?
Ans. Plants produce carbohydrate using photosynthesis process.
Ques-6. What is chemical fertilizer?
Ans. Chemical made of different elements such as carbon, oxygen, nitrogen, phosphorus that gives nutrition for the plant in the soil is called chemical fertilizer.
Ques-7. What are preservatives?
Ans. The chemicals that are used in a certain amount to store foods for a long time are called preservatives.
Ques-8. What is research?
Ans. The process to learn knowledge by experimenting is known as research.
Ques-9. What is called a chemistry laboratory?
Ans. The place where experiments or researches on chemistry are done, is called chemistry laboratory.
Ques-10. What is combustible substance?
Ans. The substances that easily catch fire and produce a lot of heat are called combustible substances.
Comprehension-based Questions & Answers:
Ques-1. Why is chemistry called central science?
Ans. Chemistry has a deep relation with all branches of science. Chemistry plays a major role in understanding the mystery of life in medical science, investigating the cause of diseases and their treatment. Physics mainly works with bodies which are made of atoms and molecules. So, chemistry is really important in developing proper knowledge in physics. The base of computer science is semiconductor and computer chips and LCD requires liquid crystal. Chemistry plays the main role in preparing and purifying them. These are the reasons why chemistry is called central science.
Ques-2. Describe the effect of chemical fertilizer?
Ans. Chemical fertilizers contain different growth enhancing elements for plants. For example, oxygen, nitrogen, phosphorus, potassium etc. This is why crop production increases when chemical fertilizers are used. But excessive use of chemical fertilizers harm plants and causes environmental pollution.
Ques-3. What is the importance of research in the present world?
Ans. Our lives have become beautiful, works have become easy, quality of life has developed all thanks to science. The role of science is huge in education, treatment, agriculture, communication and in all other sectors. This role of science has been possible only because of research. So, there is no alternative of research when it comes to technological development and solving remaining problems.
Ques-4. Why is primary knowledge necessary before experimenting with a chemical?
Ans. A lot of chemicals are harmful for health and environment directly or indirectly. A lot of chemicals can easily explode. They are toxic, combustible, health sensitive or carcinogenic. So, it is really important to know about the effects of a chemical before collecting and experimenting with it.
Ques-5. What do we know by the symbol of flame over a circle?
Ans. The symbol of flame over a circle indicates oxidizing substance. Combustible substances usually explode when they come in contact with oxidizing substances. Since the chemicals with this symbol can oxidize other chemicals so oxidant sensitive chemicals should always be kept at a safe distance from them and it should be made sure that they don’t come in contact with any combustible susbtance. We should wear apron while working with these chemicals. For example- O2, H202, HNO3, KMnO4, KNO, these are oxidizing substances.