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प्रश्न
A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset, but after a futile argument, the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
उत्तर
The solution he used was Aqua regia, a Latin word meaning ‘Royal Water’. It is a mixture of concentrated Hydrochloric acid and concentrated nitric acid in a ratio of 3 : 1. It is capable of dissolving metals like Gold and Platinum. Since the outer layer of the gold bangles was dissolved in aqua regia, their weight was reduced drastically.
संबंधित प्रश्न
Give reasons.
Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
M is a metal above hydrogen in the activity series and its oxide has the formula M2O. This oxide when dissolved in water forms the corresponding hydroxide which is a good conductor of electricity. In the above context, answer the following:
1) What kind of combination exists between M and O?
2)How many electrons are there in the outermost shell of M?
3) Name the group to which M belongs.
4) State the reaction taking place at the cathode.
5) Name the product at the anode.
Name a reducing agent that may be used to obtain manganese from manganese dioxide.
What is meant by the 'concentration of ore'?
Name one ore of copper (other than cuprite). Which compound of copper is present in this ore? Also, write its chemical formula.
Explain how, mercury is extracted from its sulphide ore (cinnabar). Give equations of the reactions involved.
Calamine ore can be used to extract one of the following metals. This metal is:
(a) copper
(b) mercury
(c) aluminium
(d) zinc
Rock salt is an ore of one of the following metals. This metal is:
(a) Mn
(b) Na
(c) Fe
(d) Cu
Which method of refining is used to get 99.8% pure aluminium?
choose the most appropriate term to match the given description.
Heating of the ore in the absence of air to high temperature
Name the methods by which concentrated ore is converted to metallic oxide.
_______ is the least reactive metal.
Bauxite reacts with sodium hydroxide in the Bayer’s process.
Explain the concept of Calcination.
Explain the following reaction with the balanced equation.
Zinc sulphide is heated strongly in excess of air
Observe the following diagram and write answers.
- Name the method.
- Write anode reaction and cathode reaction.
- Why fluorspar and cryolite are added in the mixture?
The process in which a carbonate ore is heated strongly in the absence of air to convert it into metal oxide is called ____________.
Which of the following ore is concentrated by the Froth floatation process?
During extraction of metals, electolytic refining is used to obtain pure metals.
(a) Which material will be used as anode and cathode for refining of silver metal by this process?
(b) Suggest a suitable electrolyte also.
(c) In this electrolytic cell, where do we get pure silver after passing electric current?
