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प्रश्न
Which among the following are physical or chemical change?
Evaporation of petrol
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उत्तर
Physical
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संबंधित प्रश्न
The chemical formula for rust is.............. .
In the following reaction between lead sulphide and hydrogen peroxide:
PbS (s) + 4H2O2(aq) → PbSO4(s) + 4H2O(1)
(a) which substance is reduced?
(b) Which substance is oxidised?
Fill in the following blanks with suitable words:
The addition of oxygen to a substance is called ......... whereas removal of oxygen is called ........
Explain reduction in terms of gain or loss of oxygen with one example.
In order to prevent the spoilage of potato chips, they are packed in plastic bags in an atmosphere of:
(a) Cl2
(b) H2
(c) N2
(d) O2
The process of respiration is:
(a) an oxidation reaction which is endothermic
(b) a reduction reaction which is exothermic
(c) a combination reaction which is endothermic
(d) an oxidation reaction which is exothermic
Give scientific reason.
It is reccommended to use air tight container for storing oil for long time.
Give the general group study of hydrogen with reference to
reducing power
Reacting with water, an active metal produces
With reference to oxidation & reduction reaction – complete the statement given by filling in the blanks with only the words (a) Addition (b) Removal.
‘Oxidation is a chemical reaction involving ____ of oxygen to a substance or ____ of hydrogen from a substance. Reduction on the otherhand involves ____ of hydrogen to a substance or ____ of oxygen from a substance.
Explain the term reduction in term of addition and removal of oxygen/hydrogen with a suitable example.
Give two test for an oxidising agent.
Identify the following reactions as oxidation or reduction
- Na → Na+ + e
- Fe3+ + 2 e- → Fe+
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
`2"Mg" + "O"_2 -> 2"MgO"`
During the reaction of some metals with dilute hydrochloric acid, following observations are made.
The temperature of the reaction mixture rises when aluminium (Al) is added.
Explain this observation giving suitable reason.
You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dilute HCl, dilute HNO3, ZnCl2 and water. In which of the above containers, can these solutions be kept?
Write a short note on oxidizing and reducing agents.
A reddish brown metal used in electrical wires when powdered and heated strongly turns black. When hydrogen gas is passed over this black substance, it regains its original colour. Based on this information answer the following questions:
- Name the metal and the black substance formed.
- Write balanced chemical equations for the two reactions involved in the above information
