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प्रश्न
Which among the following are physical or chemical change?
Heating of an iron rod to red hot
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उत्तर
Physical
APPEARS IN
संबंधित प्रश्न
The chemical formula for rust is.............. .
Identify the substances that are oxidised and the substances that are reduced in the following reaction.
\[\ce{4Na(s) + O2(g) -> 2Na2O(s)}\]
A shiny brown-coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black-colored compound formed.
Explain the following in terms of gain or loss of oxygen with one example:
Oxidation
When a magnesium ribbon is heated, it burns in air to form magnesium oxide. Write a balanced chemical equation for this reaction. Name
- substance oxidised, and
- substance reduced.
Define an oxidation reaction.
Explain the following in term of gain or loss of oxygen with two examples.
Oxidation
Name:
a solid that is an oxidizing agent.
Explain the term redox reaction with an example involving the reaction of hydrogen sulphide with chlorine.
When the positive charge on an ion increases or the negative charge on them decreases it is called as _______.
Explain the following reaction with their balanced chemical equation.
Hydrogen sulphide reacts with sulphur dioxide.
When Ag is exposed to air it gets a black coating of ____________.
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.
Silver metal does not show any change
Explain this observation giving suitable reason.
______ is a metal that has a high resistance to corrosion.
What are redox reactions? Give examples.
Find the oxidation number of the element in the following compound.
Ca in CaH2
State whether the given chemical reaction is a redox reaction or not. Justify your answer.
\[\ce{MnO_2 + 4HCl->MnCl_2 +2H_2O + Cl_2}\]
State the change in colour observed in following case mentioning the reason:
Copper powder is strongly heated in air.
