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प्रश्न
True or false
New substances are formed in a chemical change.
विकल्प
True
False
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उत्तर
True
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संबंधित प्रश्न
Complete and balance the following chemical equations:
N2 + O2 →
Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.
\[\ce{NH3_{(g)} + HCl_{(g)} -> NH4Cl_{(s)}}\]
TRUE \ FALSE
Evaporation of water is a physical change. True or false ?
State four conditions necessary for a chemical reaction to take place.
| Reactants | Products | Type of chemical reaction |
| BaCl2(aq) + ZnSO4(aq) | H2CO3(aq) | Displacement |
| 2AgCl(s) | FeSO4(aq) + Cu(s) | Combination |
| CuSO4(aq) + Fe(s) | BaSO4↓ + ZnCl2(aq) | Decomposition |
| H2O(l) + CO2(g) | 2Ag(s) + Cl2(g) | Double displacement |
Explain by writing a word equation.
Hard water gets softened on mixing with a solution of washing soda.
Write the chemical reaction where the following changes are observed.
Colour change is noticed
State the original colour of the following substance and colour of residue obtained after heating.
Zinc carbonate
Give balanced equation for the following conversion affected by heat alone on the substance:
Copper nitrate to nitrogen dioxide
The chemical change is ______.
Explain the following statement: Digestion is a chemical change.
A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?
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.
Which of the following statement is incorrect for a chemical reaction?
Give an example of a chemical reaction for the following situation:
A change in colour is observed
Magnesium + oxygen → magnesium oxide.
2Mg + O2 → 2Mg O
We are advised to not to play with fireworks. Give reason.
Write a note on the following:
Fermentation
______ is the chemical name of slaked lime.
Write the effects of chemical reactions.
