Advertisements
Advertisements
प्रश्न
Give one example that illustrates the following characteristics of a chemical reaction:
Change in state
उत्तर
The reaction between hydrogen sulphide and chlorine (both gases) produces sulphur (solid) and hydrogen chloride (gas).
\[\ce{\underset{Hydrogen sulphide}{H2S_{(g)}} + \underset{Chlorine}{Cl2_{(g)}}-> \underset{Hydrogen chloride}{2HCl_{(g)}} + \underset{(yellow solid)}{\underset{Sulphur}{S_{(s)}}}}\]
APPEARS IN
संबंधित प्रश्न
Complete and balance the following chemical equations
Na + H2 O →
Define catalyst.
What do you observe when Iron nail is kept in copper sulphate solution for sometime.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Miscible liquids having slightly different boiling points can be separated by the
- evaporation
- distillation
- fractional distillation
- sedimentation
FILL IN THE BLANK
Negatively charged ions are called ..........
FILL IN THE BLANK
Positively charged ions are called ........
How is a strong electrolyte different from a weak electrolyte?
Fill in the blank.
Melting of ice is a _______ change.
State four conditions necessary for chemical reactions to take place.
Write true or false :
Hydrogen sulphide has rotten egg smell .
Give an example of a reaction where the following are involved
Heat
Give an example of a reaction where the following are involved
Electricity
Define Photochemical reaction
Give an example
Give reason for the following:
Silver nitrate solution is kept in coloured bottles.
Give an example of the following chemical changes.
A reaction where colour change is noticed.
Name: Two carbonates do not produce carbon dioxide on heating.
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 acid to an active metal.
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.
Photosynthesis is a chemical reaction that takes place in the presence of ______.
Chemical change is a temporary change.
The percentage composition of Nitrogen in Ureas is ______.
Arrange the following statements in correct sequence:
- One side is water-loving and other water-hating molecules.
- When you agitate the cloth, the dirt is surrounded by many molecules and taken away from the cloth.
- The dirt surrounded by the detergent molecules floats in the water making it dirty.
- Finally, the cloth is clean.
- The detergent molecules have two sides.
- Water hating goes and joins with dirt and oil in the cloth while the water-loving joins with the water molecules.
Classify each of the following, as a physical or a chemical change. Give reasons.
(a) Drying of a shirt in the sun.
(b) Rising of hot air over a radiator.
(c) Burning of kerosene in a lantern.
(d) Change the colour of black tea by adding lemon juice to it.
(e) Churning of milk cream to get butter.
Which of the following is/are true when milk changes into curd?
- Its state is changed from liquid to semi-solid.
- It changes colour.
- It changes the taste.
- The change cannot be reversed.
Choose the correct option from below:
Beating an egg to make a cake is a ______.
______ occurs in the absence of air and in the presence of micro-organisms such as yeast.
Match the following:
| Column I | Column II | ||
| 1. | Burning of coal | a. | Rusting |
| 2. | Painting of a surface | b. | Evaporation |
| 3. | Dipping iron in the water | c. | Chemical change |
| 4. | Salt from seawater | d. | Prevention of rusting |
Write a note on the following:
Curdling of milk
Write the characteristics of chemical change.
What is the difference between reactants and products?
