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प्रश्न
Care must be taken while diluting concentrated nitric acid with water. Why?
उत्तर
A highly exothermic reaction occurs when an acid or a base dissolves in water. Mixing concentrated nitric acid with water requires caution. Always slowly pour the acid into the water while stirring constantly. The heat produced when water is added to a concentrated acid can cause the mixture to splash out and hurt people's bums. Additionally, excessive local heating could cause the glass container to shatter.
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संबंधित प्रश्न
Name two metals which are found in nature in the free state.
Metallic oxides of zinc, magnesium and copper were heated with the following metals.
| Metal | Zinc | Magnesium | Copper |
| Zinc oxide | – | – | – |
| Magnesium oxide | – | – | – |
| Copper oxide | – | – | – |
In which cases will you find displacement reactions taking place?
How many carats is pure gold? Why is pure gold not suitable for making ornaments?
Why does a new aluminium vessel lose shine so soon after use?
Name one metal which is extracted by reduction with aluminium.
Name the gas evolved when cinnabar ore is roasted.
Give the principles of the froth floatation process.
To protect iron from rusting, it is coated with a thin layer of zinc. Name the process.
Explain the following reaction with the balanced equation.
Chlorine dissolved in water
Answer the questions on the following passage.
The minerals from which the metal can be separated economically are called ores. Ores contain many types of impurities such as soil, sand and rocky substances along with metal compounds. These impurities are called gangue.
Metals can be extracted from their ores by means of various methods of separation. The process of extraction of metal in a pure state from the ores is also a part of metallurgy.
Ores are taken out from the mines and the gangue is usually separated from the ore at the site itself by various methods. Then the ores are carried out to the place where metals are produced. Here metals are extracted in pure form. Then metals are further purified by different methods of purification. This entire process is called metallurgy. Most metals being reactive do not occur in nature in the free state but are found in combined state as their salts such as oxides, carbonates, sulphides, and nitrates. however, the most unreactive metals that are not affected by air, water and other natural factors like silver, gold, platinum, generally occur in a free state. The compounds of metals that occur in nature along with the impurities are called minerals.
- What are ores?
- Which processes are involved in the branch of metallurgy? What is metallurgy?
- Which metals are found in a free state?
- In what forms are metals found in combined state?
- What is gangue?
