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प्रश्न
What is a chemical change? Give two examples of chemical change?
उत्तर
A chemical change is a permanent change in which the chemical composition of a substance is changed and a new substance is formed.
Examples:
Heating of copper carbonate
Formation of curd from milk
APPEARS IN
संबंधित प्रश्न
Complete and balance the following chemical equations:
\[\ce{Pb(NO3)2->[heat]}\] _________
Fill in the blank
A catalyst either ................or ............... the rate of a chemical change but itself remains ............... at the end of the reaction.
Define precipitation.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer
Which of the following is a reducing agent?
- oxygen
- chlorine
- hydrogen
- none of these
Copper carbonate when heated, it turns :
Explain by writing a word equation.
Limestone powder disappears on adding to dilute hydrochloric acids.
Match the pairs.
| a. | Photosynthesis | i. | Tendency to lose electrons |
| b. | Water | ii. | Reactant in combustion process |
| c. | Sodium chloride | iii. | Chemical change |
| d. | Dissolution of salt in water | iv. | Covalent bond |
| e. | Carbon | v. | Ionic bond |
| f. | Fluorine | vi. | Physical change |
| g. | Magnesium | vii. | Tendency to form anion |
Define the following terms
Precipitate
Give an example of a reaction where the following are involved
Pressure
State the type of reactions for the following represent and balance the ones that are not balanced.
NaOH + HCl → NaCl + H2O
What do you observe? When
Water is added to the quick lime.
Give a chemical test to distinguish between the following gases.
H2 and O2
Give a chemical test to distinguish between the following gases.
NH3 and HCl
Distinguish by heating the following in dry test tubs.
Zinc nitrate and copper nitrate.
Give a balanced equation for a reaction involving the evolution of gas on the addition of dilute acid to calcium carbonate.
Silver metal can displace hydrogen gas from nitric acid.
Burning of paper is the best example of ______ change.
Match the following:
| 1. | Sodium Chloride | a. | CaSO41/2H2O |
| 2. | Calcium sulphate dihydrate | b. | C2H5Oh |
| 3. | Magnesium sulphate hydrate | c. | CaSO4.2H2O |
| 4. | Calcium sulphate hemihydrate | d. | NaCl |
| 5. | Phenol | e. | MgSO4.H2O |
Magnesium + oxygen → magnesium oxide.
2Mg + O2 → 2Mg O
