Advertisements
Advertisements
प्रश्न
Fill in the blank.
The formation of gas bubbles in a liquid during a reaction is called ......................
Advertisements
उत्तर
The formation of gas bubbles in a liquid during a reaction is called effervesence
APPEARS IN
संबंधित प्रश्न
How do the following help in bringing about a chemical change?
heat.
Write the missing reactants and products and balance the equations.
\[\ce{KClO3 ->[heat]}\] ___________+ ____________
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Which one of the following alters the rate of the chemical reaction without itself undergoing any change?
- temperature and Pressure
- concentration of reactants
- presence of catalyst
- none of these
Fill in the blank
A new substance is formed in a _______ change.
Copper carbonate when heated, it turns :
Explain by writing a word equation.
Limestone powder disappears on adding to dilute hydrochloric acids.
Define a photochemical reaction.
What do you observe when HCI is passed through a silver nitrate solution.
What do you observe when Cl2 is passed through potassium iodide (KI) solution.
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 dilute hydrochloric acid to silver nitrate.
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.
Complete the table given below.
| Heat on sodium chloride | Colour imparted to flame during flame test |
State the following reaction represent oxidation or reduction.
\[\ce{Ag->Ag+}\]
State the following reaction represent oxidation or reduction.
\[\ce{Al->Al+++}\]
Assertion: The formation of iron oxide from iron is a chemical change.
Reason: For the rust to form from iron, it must be exposed to air and water.
State whether the following statement is true or false:
When a candle burns, both physical and chemical changes take place.
If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
Can you change rust back into iron by some simple method?
How can we prevent rusting?
Both CO2 and H2 gases are ______.
