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प्रश्न
True or false
New substances are formed in a chemical change.
पर्याय
True
False
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उत्तर
True
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संबंधित प्रश्न
Define chemical reaction.
Write true or false :
No new substance is formed during a chemical reaction.
Write true or false .
A black residue is formed when sugar is heated .
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)
Rusting of iron is a ______ chemical change.
Give an example of the following chemical change.
Two solids combine to form a liquid
Multiple choice:
A reaction of a type: AB + CD → AD + CD, involves
Multiple choice:
Thermal decomposition of sodium carbonate will produce
Complete and balance the following reaction:
NaCl(aq) + AgNO3(aq) →
Name the gases which turn moist red litmus blue.
Give a chemical test to distinguish between the following gases.
SO2 and Cl2
Give a chemical test to distinguish between the following gases.
NH3 and SO2
Give examples of exothermic reactions i.e. heat evolved in each of the following:
(a) reaction between a solid and a liquid
(b) reaction between two gases
Give two examples of exothermic reactions seen in everyday life.
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 – Addition of water to quicklime.
State the following reaction represent oxidation or reduction.
\[\ce{Fe++->Fe+++}\]
Explain with the help of balanced equations, how precipitation reactions are used for identifying the positive radicals in three different salts, each having a different cation [positive ion].
Differentiate between the following:
Neutralization reaction and a precipitation reaction.
What happens when cane sugar is strongly heated? Mention any two changes in it.
Classify the following processes into physical or chemical changes:
- Beating of aluminium metal to make aluminium foil.
- Digestion of food.
- Cutting of a log of wood into pieces.
- Burning of crackers.
Explain how the painting of an iron gate prevents it from rusting.
Write the characteristics of chemical change.
