Last updated on February 6th, 2024 at 12:50 am
- Which of these is not a characteristic of chemical reaction?
(a) production of heat (b) change in colour
(c) liberation of gas (d) formation of no new substance
(d) Formation of no new substance
- 2KClO3 2KCl + 3O2 is a reactions :-
(a) combination (b) decomposition
(c) displacement (d) neutralization
(b) Decomposition
Write the type of chemical reaction
- NH3 + HCl → NH4Cl – Combination Reaction
- NaOH + HCl → NaCl + H2O – Neutralization Reaction
- 2NH3 → N2 + 3H2 – Decomposition Reaction
- CuSO4 + Zn → ZnSO4 + Cu – Displacement Reaction
Answer the following questions :-
When calcium carbonate is heated we get calcium oxide and carbon dioxide.
CaCO3 CaO + CO2
When calcium carbonate is heated, it undergoes a decomposition reaction. Reactants: CaCO3. Products: CaO and CO2.
Give two examples for each of the following reactions in which –
Precipitate is formed
Precipitate Formation: AgNO3 + NaCl → AgCl, Ca(OH)2 + CO2 → CaCO3
Heat is liberated
Heat Liberation: Combustion of wood, HCl + NaOH → NaCl + H2O
Colour is changed.
Color Change: Reaction between copper sulfate and zinc, AgNO3 + NH3 → Ag(NH3)2NO3
Some reactions are given below. Identify the chemical reaction and write the reasons.
- Melting of Ice: Physical change.
- Dissolution of Sugar in Water: Physical change.
- Burning of Wood: Combustion reaction.
- Blackening of Potatoes: Oxidation reaction.
- Melting of Wax: Physical change.
- Blackening of Silver Ornaments: Chemical reaction (formation of silver sulfide).
- Souring of Milk: Biological reaction (fermentation).
- Synthesis of Food by Plants: Photosynthesis (chemical change).
Point out the difference between-
Oxidation and reduction
Oxidation and Reduction: Oxidation involves gaining oxygen or losing electrons, while reduction involves losing oxygen or gaining electrons.
Combination and decomposition
Combination and Decomposition: Combination reactions form a single product, while decomposition reactions break down a single reactant into multiple products.
Write the characteristics of a chemical reaction.
Characteristics of a Chemical Reaction:
Liberation of gas, color change, formation of precipitates, heat changes, and changes in states of matter.
When Seema tasted glucose, she felt cold in tongue. Why did she feel so? What is this reaction called ?
Seema felt cold in her tongue after tasting glucose because dissolving glucose in the mouth is an endothermic reaction, absorbing heat from the surroundings.
