Name one metal which is poor conductor of heat
2) Name one metal and non-metal which exist in liquid state at room temperature
3) What are amphoteric coides give examples
4) Name two metals which will displace hydrogen from dilute acids and two
metals which will not displace.
5) Why caesium and gallium melt in our palm
6) Why magnesium ribbon starts floating in hot water
7) Name a non-metal which is lustrous and a metal which is non-lustrous
8) Name to solid metals and two solidnonmetals along with their symbols.
9) Name two metals that starts floating after sometime when immersed in water
10) Compare the properties of a metal and a non-metal on the basis of the nature
oxide formed by them
11) Write the main difference between metals and non-metals on the basis of
chemical properties
petals in the decreasing
Answers
Answer:
Explanation: Give an example of a metal which (i) is a liquid at room temperature. (ii) cart be easily cut with knife. (iii) is the best conductor of heat. (iv) is a poor conductor of heat.Ans. (i) Mercury (Hg) (ii) Sodium and potassium (iii) Silver and copper (iv) Lead -.
2. Explain the meanings of malleable and ductile.Ans. Malleable: A metal is said to be malleable if it can be beaten into thin sheets, e.g. silver and gold are the best malleable metals. Ductile: A metal is said to be ductile when it can be drawn into thin wires, e.g. silver and gold are the best ductile metals.
3. Why is sodium kept immersed in kerosene oil?Ans. Sodium is highly reactive metal. It reacts with oxygen in air at room temperature, the reaction is highly exothermic. To prevent this sodium is kept preserved under kerosene. Sodium does not react with kerosene.
4. Write equations for the reactions of (i) iron with steam (ii) calcium and potassium with waterAns. (i) Iron with steam
Answer:
1) Lead is the poorest conductor of heat.
Explanation:
Lead is a chemical element with symbol Pb(from the Latin plumbum) and atomic number 82. It is a heavy metal. Lead is soft and malleable, and has a relatively low melting point.
Its electronegativity is -2,
it is poor conductor of heat because it readily reacts with the atmosphere to form lead oxide, where we know metal oxides are poor conductor of heat and electricity as well.
2) The metal which exist as a liquid at room temperature is mercury. Non-metal which exist as a liquid at room temperature is bromine.
3) Oxides of metals having both basic and acidic characteristics are called amphoteric oxides. For example, zinc oxide & aluminum oxide.
Explanation:
These oxides have dual character and can act as both base and acid while undergoing reactions to form salts and water molecules.
Metals having multiple oxidation states can form amphoteric oxides. Let us look at the example of Aluminium Oxide.
When it is reacted with an acid such as HCl it takes the characteristics of a base and forms the compound AlCl_3.AlCl
3
.
While reacting with a base such as NaOH it takes acidic characteristics and forms the compound called NaAlO_2.NaAlO
2
4) Iron and aluminium will displace hydrogen from dilute acids as they more reactive then hydrogen. Mercury and copper cannot displace hydrogen from dilute acids as they are less reactive than hydrogen.
5) A chip of gallium or caesium melts on our palm because the melting point of these metals is just below thirty degrees Celsius 86oF. They have very low melting point. b Magnesium reacts with hot water and starts floating due to the bubbles of hydrogen gas sticking to its surface
6) Magnesium hydroxide formed during the reaction of magnesium with water in hot air is insoluble in the water and deposits on the surface of the magnesium ribbon. ... The Hydrogen gas formed at the initial stage of the reaction bubbles on the surface of the magnesium ribbon and makes magnesium ribbon lighter than water.
7) Bromine (non-metal) is lustrous. Sodium (metal) is non-lustrons due to the formation of an oxide layer on its surface.
8) Iron(Fe) and copper(Cu) are solid metals at room temperature. Carbon(C) and sulphur(S) are non-metals which are solids at room temperature.
9) calcium and lithium . this is because when calcium is immersed in water it reacts with water . which forms calcium hydroxide. and releases the hydrogen.
10) (1)- metal oxides are basic in nature and non metal oxides are acidic in nature. (2)- most metals conduct electricity and heat and non metals cannot conduct electricity and heat. (3) mostly all metals are lustrous.
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