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What is"hydraulic washing" or "gravity separation"?explain with diagram
the galvanised article is protected against rusting even if zinc coating is broken
a large no; of thin black strips are painted an a concave mirror ,the image on a distant white horse will be----------options-a] a zebra b]white horse c] black horse d]darker white house e]dimmer white horse.
why are metals called electropositive elements whereas non-metals are called electronegative elements?
Hydrogen gas is not evolved when nitric acid reacts with metals but magnesium and manganese metals react with nitric acid to produce hydrogen gas,why??HOW?
difference between calcination and roasting
what are amphoteric oxides? give 2 examples
alloys are used in electrical heating device rather than pure metal .give two reasons for this statement ?
Silver and gold do not react with oxygen even at high temperatures.but yet silver and gold turn to some other colour after a few years or months. how is it so?
what is the nature of metal oxide and non metallic oxide? give reason
Why is glass wool used for the expire meant to test the action of steam on metal
Most of the metals do not give hydrogen while reacting with nitric acid. Why ?
why tarnished copper vessels are cleaned with lime juice or tamarind
Iron is a strong metal, yet never used in pure state. Give reasons
Explain with example - calcination and roasting
(i) Explain the steps for extraction of copper from its sulphide ore. Write the balanced equations involved in the process. (ii) What is meant by refining of metals ? Draw a diagram of electrolytic refining of copper and name the substances used as cathode, anode and the electrolyte.
what are the uses of metals and non -metals???????
Explain why conc. HNO3 can be stored in aluminium container
What is melting point of gallium and caesium
why are metals sulphide and carbonate converted into metal oxide prior to reduction during the extraction of metals . explain by giving one example in each case
Non metal generally donot displaces hydrogen from dilute acid ? why
why electric wire coated with PVC ?
why metal oxides are basic in nature?
copper vessels get a green coat when exposed to air in rainy season
why oxdes of very reactive metals cannot be reduced with carbon ? how these metals are obtained from their ores?
why zinc is used in the galvanisation of iron and not the copper?
Name two metals alloyed with iron to make stainless steel.
Why Magnesium , Manganese does react with dilute HNO3 to evolve hydrogen gas
while other metals dont produce hydrogen gas when reacted with HNO3
An ore on treatment with dilute hydrochloric acid produces brisk effervescence. What type of ore is this? What steps will be required to obtain metal from the enriched ore?
name the gas evolved when dilute hcl reacts with sodium hydrogen carbonate. how is it recognised?
2Al(s) + 3H2O(g) -------- Al2O3(s) + 3H2(g)
why in the above reaction metal oxide is formed? why not metal hydroxide?
What is the difference b/w electrolytic reduction and electrolytic refining?
Name the constituents and uses of Brass,Bronze and Solder.
1)Gold ans silver are used to make jewellery.
2)Carbonate and sulphide ores are usually converted into oxides prior to reduction during the process of extraction.
Is sodium nitrate, an acidic or a basic salt?
why metal are not found in free state generally?
Differenciate between Flux and Slag.
. What are antacids? Name two compounds which are used as antacids
give reasons why cooking utensils are made up of metals like copper, aluminium etc
Write the electron dot structure for sodium and chlorine atoms. How do these form a chemical Bond? Name the type bond so formed why does a compound so formed have high melting point?
is H2SO4 an ionic compound or a covalent compound? what is the electronic dot structure of H2SO4 ?
) Define an alloy. How are alloys prepared ? How do the properties of iron change when : (i) small quantity of carbon, (ii) nickel and chromium are mixed with it.
Why are metals sonorous? Which metal is the most sonorous?
explain giving equation, what happens when:
ZNCO3 is heated in the absence of air?
a mixture of CU2O and CU2S is heated?
when we take pieces of iron ,zinc,lead,and copper ,when we place one metal on a block of iron and strike it four or five times with a hammer . what happens .
A, B and C are three elements which undergo chemical reactions according to the following equations.
metals replace hydrogen from acids whereas non metal do not. give reason
metals are good conductors of electricity wheereas non metals are not .give reason
which metal occurs in free state in the earth's crust
Explain how the following metals are obtained from their compounds by the reduction process.
1) metal X which is low in the reactivity series
2) metal Y which is the middle of the reactivity series
3) metal Z which is high in the reactivity series
.Give an eg of each
what is electrolytic reduction ???
How to remember REACTIVITY SERIES?
WITH A LABEL DIAGRAM DESCRIBE AN ACTIVITY TO SHOW THAT METALS ARE GOOD CONDUCTOR OF ELECTRIITY.
do u know how to keep reactivity series of metals in mind
Why Aluminium Oxide and Zinc Oxide is called Amphoteric Oxides?
it would have been better like this :
1. Metallic Lustre: The surface of most metals is shiny. The lustre associated with metals is known as metallic lustre. For example, iron, copper, gold, and silver are very shiny. Metals such as gold and silver are very lustrous. Therefore, they are used for making jewellery.
Some metals do not look very lustrous. This is because they either lose their lustre or their lustre gets reduced when exposed to air for a long time. This happens due to the formation of a layer of oxide, carbonate, and sulphide on their surface. If a metal surface is rubbed with sand paper, then this layer gets removed and the shiny surface of the metal can be seen. The layer formed in some cases is stable and sticks on the surface of the metal, but in other cases, it is unstable and falls off (as in the case of rusting of iron).
1. Lustre: Non-metals do not have a shiny surface. However, iodine is an exception, which has a very shiny surface.
2. Hardness: Metals are generally hard in nature. However, this hardness varies from metal to metal. Most metals such as iron, aluminium, etc. are very hard and cannot be cut with a knife whereas some metals such as sodium and potassium are very soft and can be cut using a knife.
2. Hardness: Non-metals generally exist as solids, liquids, or gases. Non-metals that exist in a solid state are very soft. For example, sulphur, which exists in solid state, is quite soft. Similarly, carbon, in the form of graphite, is quite soft. However, diamond, another allotrope of carbon, is very hard. It is in fact the hardest known natural substance.
3. Malleability: Metals are malleable. Most metals such as iron, copper, silver, and gold can be hammered without breaking to form thin sheets. Aluminium, copper, and silver are highly malleable metals and are often used for making foils, which are extensively used in the decoration of sweets, packing of food items, etc
3. Malleability : Non-metals that exist in solid states are not very strong. They are brittle and break when pressure is applied on them. Therefore, non-metals are not malleable
4. Ductility: Most metals are ductile, which means that they can be drawn into thin wires without breaking. For example, iron, copper, silver, and gold can be drawn into thin wires without breaking. For this reason, copper and aluminium are extensively used for making electrical wires.
4. Ductility:Non-metals that exist in solid states are not very strong. They are brittle and break when pressure is applied on them. Therefore, non-metals are not ductible.
5. Conduction of heat: Metals are generally good conductors of heat. This means that if one end of a metal rod is heated for some time, then the entire rod becomes hot. For example, aluminium, copper, and silver are good conductors of heat. Hence, copper and aluminium are generally used for making vessels. The following activity can be performed to explain that metals can conduct heat .
5. Conduction of heat :Non-metals are poor conductors of heat and electricity. Examples include sulphur and phosphorus.
6. Conduction of electricity: Metals are good conductors of electricity i.e., they allow an electric current to pass through them easily. Silver, copper, and aluminium are the best conductors of electricity. For this reason, most electric wires are made of copper and aluminium. However, using silver for making electric wires is not cost effective. The following activity can be performed to explain that metals can conduct electricity.
6.Coductuin of electricity : Non-metals are poor conductors of heat and electricity. Examples include sulphur and phosphorus. However, there is an exception. Graphite, an allotrope of carbon, is a good conductor of electricity.
7. Melting and boiling points: Melting and boiling points of metals are usually high.
7. Melting and boiling points: Melting and boiling points of non-metals are quite low. For example, the melting point of phosphorus is 44.2°C. However, diamond, an allotrope of carbon, is the only non-metallic substance that has a very high melting and boiling point. The melting point of diamond is more than 3500°C.
8. Physical state: All metals exist as solids at room temperature except mercury, which exists as a liquid.
8. Physical state: Non-metals exist in all three physical states at room temperature. Non-metals such as carbon, sulphur, and phosphorus exist in solid states while oxygen, chlorine, and nitrogen exist in gaseous states. Bromine is the only non-metal that exists in a liquid state.
Why hydrogen comes in reactivity series of metals????andHow reactivity of hydrogen can be found out????????
name the metal which reacts with a very dilute HNO3 to evolve hydrogen gas?
why sodium hydroxide can not be stored in aluminium containers ?
name one metal and one non-metal which exist in liquid state at room temperature
Aluminium occurs in combined state in nature whereas, gold occurs in free state. Why?
what is electrolytic refining ? explain
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