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प्रश्न
Fill in the blank:
The substances which undergo chemical change are called _______
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उत्तर
The substances which undergo chemical change are called reactants .
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संबंधित प्रश्न
How do the following help in bringing about a chemical change?
light.
TRUE \ FALSE
Evaporation of water is a physical change. True or false ?
What are the characteristics of a chemical reaction ? A chemical reaction is characterised by an irreversible change in which a new substance is formed.
Fill in the blank
A new substance is formed in a _______ change.
Write true or false :
When iron and sulphur are heated together a grey mass is formed which is attracted by a magnet .
State four conditions necessary for a chemical reaction to take place.
Explain the following reaction with one suitable example of Displacement reaction.
Name the type of chemical reaction shown by the following equation :
Fe2O3 + 2Al → Al2O3 + 2Fe
Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)
A colourless solution of calcium hydroxide in a test tube turns ______ on blowing in it through a blow tube for some time.
Multiple choice:
Thermal decomposition of sodium carbonate will produce
What do you understand by 'chemical reaction'?
Give a chemical test to distinguish between the following gases.
HCl and Cl2
Write your observation and a balanced equation in the case of the following substances being heated.
Copper carbonate.
Give reason for the following:
Even though rusting is an exothermic reaction, the heat evolved when an iron nail rusts is unnoticeable.
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Thermal decomposition of mercury [II] oxide.
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.
Give balanced equation for the following conversion affected by heat alone on the substance:
Copper carbonate to copper oxide
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Copper nitrate.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Calcium hydroxide.
Iron and rust are the same substances.
