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प्रश्न
Which among the following are physical or chemical change?
Sublimation of solid ammonium chloride
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उत्तर
Physical
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संबंधित प्रश्न
A shiny brown-coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black-colored compound formed.
Fill in the following blanks with suitable words:
The addition of hydrogen to a substance is called ........ whereas removal of hydrogen is called .......
Give one example of an oxidation-reduction reaction which is also a displacement reaction.
When copper powder is heated strongly in air, it forms copper oxide. Write a balanced chemical equation for this reaction. Name (i) substance oxidised, and (ii) substance reduced.
Fill in the blank
In redox reaction oxidation and reduction occur ............................
Electrolysis is a redox process. Explain.
Explain the following in term of gain or loss of oxygen with two examples.
Oxidation
Compare hydrogen and halogens on the basis of:
reaction with oxygen
Divide the following reactions into oxidation and reduction half-reaction:
Zn + Pb2+→ Pb + Zn 2+
Which of the following statements about hydrogen is incorrect?
Complete and balance the following equation:
CuO +__________→ Cu +___________
Identify the reducing agent in the following reactions
`4"NH"_3 + 5"O"_2 -> 4"NO" + 6"H"_2"O"`
Identify the oxidising agent (oxidant) in the following reactions
`3"Fe" + 4"H"_2"O" -> "Fe"_3"O"_4 + 4"H"_2`
Which among the following are physical or chemical change?
Evaporation of petrol
During the reaction of some metals with dilute hydrochloric acid, following observations are made.
Some bubbles of a gas are seen when lead (Pb) is reacted with the acid.
Explain this observation giving suitable reason.
The tarnishing of metals is due to the formation of ______.
______ is a metal that has a high resistance to corrosion.
What is rancidity?
Define oxidation number.
When hydrogen gas is passed over black copper oxide, a reddish-coloured layer of copper is formed.
Answer the questions that follow based on this reaction.
- Write the equation.
- What type of reaction is it?
- Complete the blanks:
In this reaction, an oxygen atom goes away from CuO (copper oxide), which means that ______ of copper oxide takes place, whereas a hydrogen molecule takes up an oxygen atom and water (H2O) is formed, meaning ______ of hydrogen takes place.
