FBISE 9th Class Chemistry Chapter 8 Chemical Reactivity Short Questions Answers
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Class/Subject: 9th Class Chemistry
Chapter Name: Chemical Reactivity
Board: Federal Board
Helpful For:
- Federal Boards 9th Class Chemistry Annual Examination
- Schools 9th Class Chemistry December Test
- Federal 9th Class Chemistry Test
- Entry Test questions related Chemistry
FBISE 9th Class Chemistry Chapter 8 Chemical Reactivity Short Questions Answers
What is meant by chemical reactivity?
Chemical reactivity is measured by the reactive tendency of an element to lose or gain electrons or electrons in chemical reactions. Reactivity refers in general to the tendency of a substance to react with others.
What do you mean by the inertness of noble gases?
The chemistry of metals is characterized by their ability to lose electrons or cations. Some metals such as copper, silver, gold, and platinum are relatively difficult to oxidize. Therefore, these metals are often called noble metals. Gold and platinum exist mostly as free elements in nature. Copper and silver exist in both tree and combined states.
What do you know about non-metals?
Elements that conduct heat and electricity poorly are called non-metals.
Define metals?
Metals are the elements that are electropositive and form cations by losing electrons.
Write down any two physical properties of metals?
i. Almost all metals are solid
ii. All metals have high melting and boiling point.
Define electropositive reaction?
Metals tend to lose their electrons. This property of a metal is called the electropositive character of a metallic character. E.g.
Na → Na+ + 1e-
What type of elements are metals?
The elements are electropositive and form cations by losing electrons. This type of element is metals.
Define transition elements?
The elements in which the d-orbital are in the process of filling constitute a group of metals called transition elements.
What do you mean by 24 carats of Gold?
The purity of gold is shown by carats. That indicates the number of parts by weight a gold that is present is 24 parts of alloy. 24 carats gold is pure.
Write down two chemical properties of non-metals?
i. Nonmetals form ionic compounds with metals and covalent compounds by reacting with one another e.g. CO2, NO2, etc.
ii. Non-metals usually do not react with water.
What are halogens?
Halogens mean salt former. Elements of group-17 of the periodic table consisting of fluorine, chlorine, bromine, iodine, and astatine. They are collectively called halogens.
Why valency of chlorine is 1?
The valency of the chlorine atom is 1 because it accepts only 1 electron in its outermost shell.
Why is HF weak acid?
Because HF does not release its proton easily due to the presence of hydrogen bonding.
Write down the uses of Sodium?
i. Sodium-potassium alloy is used as a coolant in a nuclear reactor.
ii. It is used to produce yellow light in a sodium vapor lamp.
iii. It is used as a reducing agent in the extraction of metals like Ti.
Write down the uses of Calcium?
i. It is used to remove sulphur from petroleum products.
ii. It is used as a reducing agent to produce Cr, U, Zr.
Write down the uses of Magnesium?
i. Magnesium is used in flashlights and fireworks.
ii. It is used in the manufacture of light alloys.
Write down the uses of Copper?
i. It is widely used for making electrical cables, ornaments, coins, and alloys such as brass, bronze, etc.
ii. Its lightweight makes it easier to use in constructions.
Why metals are electropositive?
The tendency of a metal to lose electrons and form positive ions is called electropositive character.
The metals on the left and the lower left side of the periodic table have low ionization energies, hence these metals are electropositive. Metals like sodium, magnesium, and copper, etc. are highly electropositive.
Why non-metals are electronegative?
The tendency of non-metals to accept an electron to form an anion is called a non-metallic or electronegative character.
The elements having high electron affinity or high electronegativity have a higher tendency to gain electrons and form a negative ion. The elements in the upper-right-hand portion of the periodic table are electronegative or non-metallic.
Describe the ionization energies of alkali and alkaline earth metals?
Because alkali metals have low ionization energies, therefore have a great tendency to lose the single valence electron to form cations. They are so reactive that they are never found in the Free State.
What are metalloids?
Several elements near the stepped line have mixed properties of metals and non-metals. These metals are called metalloids.
What are noble metals?
Metals such as copper, silver, gold, and platinum are relatively difficult to oxidize. Therefore, these metals are often called noble metals.
What are Halides?
All the halogens react with metals to form salts called halides.
Write any three chemical properties of Metals?
i. Metals easily lose electrons and form positive ions.
ii. Metals readily react with oxygen to form basic oxides.
iii. Metals have metallic bonding
Write down three physical properties of Calcium?
i. Calcium is silvery grey and fairly harder.
ii. Its density is 1.55 gcm3
iii. It is malleable and ductile.
What is the nature of metallic oxides?
The metallic oxides are basic because they change red litmus paper to blue.
How platinum is used as a catalyst in automobiles and what we advantage of this use?
Platinum alloyed with palladium and rhodium is used as a catalyst in automobiles as the catalytic converter. They convert most of the gases being emitted by vehicles into less harmful carbon dioxide, nitrogen, and water vapor.
What is the importance of Mg?
Magnesium has a relatively low density and it is used in making lightweight alloy with aluminum that is used for making frames of automobiles, aircraft and space ship, cameras, etc.
What is aqua regia?
Gold and platinum react only with aqua regia. Aqua regia is a mixture of 3 parts by volume of Conc. HCl and one part by volume of Conc. HNO3.
What is the trend of variation in densities of alkali metals?
Densities of alkali metals increase down the group in the periodic table due to increase atomic mass.
