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प्रश्न
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.
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उत्तर
Thermal decomposition of mercury [II] oxides: Red colour of Hg[II]0 changes to silvery (Hg metal).
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संबंधित प्रश्न
When carbon dioxide is passed through lime water, it turns milky due to the formation of ______.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Reduction reaction is the exact opposite of
- displacement reaction
- decomposition reaction
- oxidation reaction
- none of these
FILL IN THE BLANK
........... electrolytes dissociate completely in aqueous state and allow large amount of electricity to flow through it.
FILL IN THE BLANK
Negatively charged ions are called ..........
FILL IN THE BLANK
Distillation is a method of obtaining pure ............. from a solution.
Name three reducing agents ?
Fill in the blank:
The basic conditions necessary for a chemical reaction is _______
Give an example of a reaction where the following are involved
Light
Give an example of the following chemical change.
Two solids combine to form a liquid
Multiple choice:
Thermal decomposition of sodium carbonate will produce
What do you observe? When
Water is added to the quick lime.
Name affects the acidified K2Cr2O7 paper and also turns lime water dirty milky.
Complete the following table and write your observations.
|
Hydrogen sulphide |
Ammonia |
Sulphur dioxide |
Hydrogen chloride |
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Shake the gas with red litmus solution |
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Shake the gas with blue litmus solution |
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Apply a burning splint to a gas |
State the following reaction represent oxidation or reduction.
\[\ce{Cl- ->Cl}\]
State the following reaction represent oxidation or reduction.
\[\ce{H->H+}\]
State whether the following reaction is oxidation or reduction.
\[\ce{Na->Na+}\]
Give a suitable example with an equation to show the representation of a chemical reaction.
NPK are the primary nutrients for plants.
The water we drink is a combination of hydrogen and oxygen.
We are advised to not to play with fireworks. Give reason.
