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Q.2 Write short answers to any five questions.
(i) Define physical chemistry. What is its scope?
Ans. Physical Chemistry:
Definition:
"Physical chemistry is defined as the branch of chemistry that deals with the relationship between the composition and physical properties of matter along with the changes in them."
Scope:
The properties such as structure of atoms or formation of molecules, behavior of gases liquids and solids and the study of the effect of temperature of radiation on matter, all are studied under this branch.
(i) Differentiate between organic and inorganic chemistry.
Ans. Organic Chemistry:
"Organic Chemistry is the study of covalent compound of carbon and hydrogen called hydrocarbons and their derivatives.
Inorganic Chemistry:
"Inorganic chemistry deals with the study of elements and their compounds except those of compounds of carbon and hydrogen (hydrocarbons) and their derivatives."
(iii) Define biochemistry. Give its scope.
Ans. Biochemistry:
Definition:
"It is the branch of chemistry in which we study the Structure, composition and chemical reactions of substances found in living organisms Scope:
Biochemistry covers all chemical processes taking place in living organisms. Such as synthesis and metabolism of biomolecules like carbohydrates proteins and fats
(iv) What is nuclear chemistry. Give some applications of nuclear chemistry.
Ans. Nuclear Chemistry:
Definition:
"Nuclear chemistry is the branch of chemistry that deals with the radioactivity nuclear processes and nuclear properties
Applications:
1) The main concern of this branch is with the production of energy from the atom and its uses in daily life. In other words it is used for the production of electricity through nuclear reactors.
(2) It also includes the study of the chemical tests resulting from the absorption of radiation within living animals, plants, and other materials.
(3)It has vast applications in medical treatment (radiotherapy).
(4)It is also used for preservation of food.
(v) Differentiate between physical and chemical properties? Give their examples
Ans. Types of Properties of a Substance: There are two main types of properties of a substance.
Physical Properties
"The properties that are associated with the physical state of a matter are called physical properties".
Examples: Properties of a substance like, its colour, smell, hardness, shape of a crystal, solubility, melting or boiling points, density, etc. are called physical properties of a substance.
Chemical Properties
"The properties that can be observed only when a substance undergoes a chemical change are called chemical properties of a substance"Examples: Properties like, rusting of iron, burning of coal or gasoline in air, decomposition of water during electrolysis, burning of Mg, oxidation of food in the body cells, etc. are called chemical properties of a substance
(vi) Sort out physical and chemical properties from the following: Colour, smell, rusting of iron, burning of coal, melting point, density, decomposition of water, solubility, etc.
Ans. Physical Properties:
Colour, smell, melting point, density, solubility Chemical Properties:
Rusting of iron, burning of coal, decomposition of water.
(vii) What is the modern definition of element? Give some examples of elements.
Ans. Element:
"It is a substance made up of same type of atoms, having same atomic number and it can not be decomposed into simple substances by chemical means.
Examples:
Hydrogen (H), Iron (Fe), Copper (Cu), mercury (Hg), Oxygen (0) etc. are elements.
(viii) How elements are classified according to their physical state?
Ans. Classification of Elements:
According to their physical states, elements can be classified into solids, liquids and gases.
1. Solids: Majority of the element exist as solids e.g.
sodium, copper, zinc, gold, etc.
2. Liquids: There are very few elements which occur in liquid state e.g. mercury and bromine, etc.
3. Gases: A few elements exists as gases e.g.
4. nitrogen, oxygen, chlorine and hydrogen, etc.
(iv) Differentiate between homogeneous and heterogeneous mixtures.
Ans. Homogeneous Mixture:
"A mixture having a uniform composition is called a homogeneous mixture”.
Examples: Air, petrol, natural gas, copper sulphate solution, sugar solution, etc.
Heterogeneous Mixture:
A mixture having a non-uniform composition is called a heterogeneous mixture".
Examples: Milk, blood, ice-cream, soil, rocks food-products, wood, water, etc.
(v) Define atomic number (Z) and mass number (A)?
(OR)
Define atomic number and mass number? What is the relation between mass number and atomic number of an element?
Ans. Atomic Number (Z):
"The atomic number of an element is equal to the number of protons present in the nucleus of its atoms
Symbol
It is represented by symbol "Z".Examples:
(1) All hydrogen atoms have one proton, their atomic number Z-1
(2) All atoms in the carbon have 6 protons, their atomic number Z-6
Mass Number (A):
"The mass number is the sum of number of protons and neutrons present in the nucleus of an atom."
Symbol:
It is represented by 'A'
(viii) What is meant by the theory of dual nature of matter?(OR)What is meant by corpuscular and wave nature of matter?
Ans. Corpuscular Nature of Matter: In 1924, de Broglie put forward the theory of dual nature of matter i.e. matter has both the properties of particles as well as waves. He explained the background of two ideas. He advocated that these two systems could not remain detached from each other. By mathematical evidences he proved at every moving object is attached with waves and every wave has corpuscular nature as well. It formulated a basis to understand corpuscular nature of matter.
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