CHAPTER 1 CHEMISTRY 9th TEST YOURSELF

Test yourself 1.1
(1) In which branch of chemistry behavior of gases and liquids is studied?
In physical chemistry the behavior of gases and liquids is studied.
(2) Define biochemistry.
The branch of chemistry in which we study the structure, composition and chemical reactions of substances found in living organism called bio chemistry.
(3) Which branch of chemistry deals with preparation of paints and paper?
Industrial chemistry deals with the preparation of paints and paper.
(4) In which branch of chemistry are metabolic processes of carbohydrates and proteins are studied?
In biochemistry we study the metabolic processes of carbohydrates and proteins.
(5) Which branch of chemistry deals with atomic energy and its uses in daily life?
Nuclear chemistry deals with atomic energy and its uses in daily life.
(6) Which branch of chemistry deals with structure and properties of naturally occurring molecules?
In organic chemistry we study the structure and properties of naturally occurring molecules.


Test yourself 1.2


(1) Can you identify mixture, element or compound out of the following:
coca cola, petroleum, sugar, table salt, blood, gun powder
coca cola: mixture petroleum: mixture sugar: compound table salt: compound blood: mixture gun powder: mixture
(2) How can you justify that air is a homogenous mixture. Identify substances present in it?
Air has uniform composition throughout therefore it is a homogenous mixture. It is composed of 78% nitrogen, 21% oxygen,0.9% argon and 0.03% carbon dioxide with some moisture.




(3) Name the elements represented by the following symbols:
Hg,Au,Fe,Ni,Co,W,Sn,Na,Ba,Br,Bi
Hg.... Mercury, Au.... Gold, Fe.... Iron, Ni.... Nickel, Co.... Cobalt, W... Tungsten, Sn... Tin, Na... Sodium, Ba... Barium, Br... Bromine, Bi... Bismuth
(4) Name a solid,a liquid and gaseous element that exists at the room temperature.
Solid elements: Iron, carbon
Liquid elements: Bromine, mercury
Gaseous elements: Hydrogen, oxygen
(5) What elements do the following compounds contain?
SUGAR: Carbon, oxygen and hydrogen
COMMON SALT: sodium, chlorine
LIME WATER: Calcium, oxygen and hydrogen
CHALK: calcium, carbon and oxygen


Test yourself 1.3
(1) How many amu 1g of a substance has?
Since
1 amu = 1.66 x 10^-24 g
Then, 1 g = 1 / 1.66 x 10^-24
           1 g = 9.09 x 10^23 amu
(2) Is atomic mass unit a SI unit of an atomic mass?
'amu' is not SI unit as it is not derived from the set of base units - it is really a ratio defined with respect to the C-12 atom.
(3) What is the relationship between atomic number and atomic mass?

(4) Define relative atomic mass?
The relative atomic mass of an element is the average mass of an atom of that element as compared to 1/12 th(one twelfth) the mass of an atom of carbon-12 isotope.
(5) Why atomic mass of an atom is defined as relative atomic mass?
The mass of an atom is too small to be determined practically. However, certain instruments enable us to determine the ratio of the atomic mass of various elements to that of carbon-12 atoms. This is the reason atomic mass of an atom is defined as relative atomic mass.