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प्रश्न
Fill in the blank:
The basic conditions necessary for a chemical reaction is _______
उत्तर
The basic conditions necessary for a chemical reaction is close contact .
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संबंधित प्रश्न
The chemical name of baking soda is ______.
The gas we use in the kitchen is called liquefied petroleum gas (LPG). In the cylinder, it exists as a liquid. When it comes out from the cylinder it becomes a gas (Change − A), then it burns (Change − B). The following statements pertain to these changes. Choose the correct one.
Fill in the blank.
The formation of gas bubbles in a liquid during a reaction is called ......................
TRUE \ FALSE
Temperature at which a liquid starts boiling is known as the boiling point of that liquid. True or false ?
Is kerosene an electrolyte or a non-electrolyte ?
What do you observe when :
an iron nail is kept in tap water for few days
Write true or false :
No new substance is formed during a chemical reaction.
A chemical equation is a statement that describes a chemical change in terms of
Explain the following reaction with one suitable example of Double decomposition reaction.
Choose the correct option from the bracket and explain the statement giving reason.
(Oxidation, displacement, electrolysis, reduction, zinc, copper, double displacement, decomposition)
To prevent rusting, a layer of ______ metal is applied on iron sheets.
Out of sodium and sulphur which is a metal? Explain its reaction with the oxygen.
Explain by writing a word equation.
Respiration is a chemical change.
Multiple choice:
A reaction of a type: AB + CD → AD + CD, involves
What do you observe? When
Water is added to the quick lime.
What do you observe? When
Sodium chloride solution is added to silver nitrate solution.
Name: Two nitrates that do not produce nitrogen dioxide on heating.
State the original colour of the following substance and colour of residue obtained after heating.
Ammonium dichromate
Distinguish by dilute sulphuric acid.
Sodium Sulphite and sodium carbonate?
Distinguish by dilute sulphuric acid.
Copper and magnesium?
Select the correct answer for the following options:
The pale blue precipitated obtained when copper [II] sulphate reacts with sodium hydroxide.
Give a word equation for the following reaction.
Two solids which combine on heating, to give a liquid.
Give a word equation for the following reaction.
A compound which on heating shows – colour change from brown to yellow.
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
A coloured substance which leaves a black residue and evolves two gases one of which is acidic and coloured and the other neutral and colourless.
______ gas causes tears in our eyes while cutting onions.
Analogy:
H2O: Water:: NaCl: ______.
Heat may evolve or be absorbed during a ______ change.
Galvanization is a process in which ______ is coated as a layer of iron.
The chemical name of baking soda is sodium bicarbonate.
Write the characteristics of chemical change.
