9th chemistry New Book chapter 1 Question Answer
9th chemistry New Book chapter 1 Question Answer notes.
Q1 Mention the name of the branch of Chemistry in which you will study each of the following topics.
(a) Rate of a reaction
(b) Digestion of food in human body
(c) properties of plasma
(d) Ecosystem
(e) reaction taking place during fireworks
(f) Measurement of the absorption of wavelength with the help of ultraviolet spectrometer.
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Q2 What are allotropic forms? Explain the allotropic forms of carbon and sulphur. How does coal differ from diamond?
Elements may exist in more than one structural forms which can exhibit quite different physical and chemical properties. These forms are called allotropic forms.
Carbon exists in three main allotropic forms, diamond graphite and Buckminster fullerene. Diamond has a giant macromolecular structure. Graphite has a layered structure of hexagonal rings of Carbon. In Fullerene, Carbon atoms form spherical or tube-like shape. Diamond is insulator but graphite is conductor.
Sulphur exists in two main allotropic forms. Rhombic sulphur and monoclinic sulphur. Rhombic sulphur is most stable at room temperature. It has yellow crystals. Monoclinic sulphur has yellow needle-shaped crystals.
Coal is not an allotropic form of Carbon. It is amorphous and diamond is crystalline.
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Q3 What are supercritical fluids. How are they different from ordinary liquids?
Supercritical fluid is an intermediate state of matter. Supercritical fluids are highly compressed states which show both properties of gases and liquids.
Flow of supercritical fluid is like low of gas. Density of supercritical fluid is less than the density of liquid. Supercritical fluids can move like gases but also dissolve things like liquid.
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Q4 Define solubility of a solute. How does the solubility of solutes change with the increase in temperature?
The solubility of solute is the amount of solute which can dissolve in 100 gram of a solvent at a particular temperature. Change in Solubility of a solute depends on type of solute and solvent.
The solubility of solid solute usually increases with temperature, for example sugar in water. The solubility of gases decreases with temperature, for example carbon dioxide in water.
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Q5 What types of movements are present in gaseous and liquid molecules?
In liquids and gases molecules always remain in motion. In liquids molecules slightly vibrate in place and can rotate around each other. On the other hand, molecules of gases move freely in all directions due to high kinetic energy.
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Q6 Differentiate between the areas which are studied under inorganic and organic chemistry?
Organic chemistry deals with the compounds that contain Carbon especially carbon-hydrogen bond. In organic chemistry we study hydrocarbons, Alcohols and Polymers. Inorganic chemistry deals with all elements and compounds except most Carbon compounds.
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