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Q 01 / 25
Every chemical reaction must involve a change in energy.
Q 02 / 25
Rusting of iron is a physical change.
Q 03 / 25
Magnesium reacts with oxygen to form magnesium oxide.
Q 04 / 25
In a balanced chemical equation, the mass of reactants and products is equal.
Q 05 / 25
Chemical equations must show physical states of reactants and products.
Q 06 / 25
Precipitation is a type of chemical reaction.
Q 07 / 25
All combination reactions are exothermic.
Q 08 / 25
Decomposition reactions always require heat.
Q 09 / 25
The reaction of silver chloride with sunlight is an example of a photochemical reaction.
Q 10 / 25
Respiration in living organisms is a chemical reaction.
Q 11 / 25
Oxidation always means addition of oxygen to a substance.
Q 12 / 25
In displacement reactions, a more reactive element replaces a less reactive element from its compound.
Q 13 / 25
Photosynthesis is an example of an endothermic reaction.
Q 14 / 25
All decomposition reactions are the exact opposite of combination reactions.
Q 15 / 25
Chemical equations can be balanced by adjusting the coefficients only.
Q 16 / 25
Carbon dioxide is liberated when dilute hydrochloric acid reacts with sodium carbonate.
Q 17 / 25
The formation of curd from milk is a chemical change.
Q 18 / 25
Rust is produced when iron reacts with dry oxygen only.
Q 19 / 25
Precipitate does not form in a neutralization reaction.
Q 20 / 25
A chemical reaction cannot occur without a change in color, temperature, or state.
Q 21 / 25
Photosynthesis produces heat as a product.
Q 22 / 25
The reaction between lead nitrate and potassium iodide forms a yellow precipitate.
Q 23 / 25
Double displacement reactions always result in gas formation.
Q 24 / 25
Combination reactions always require heat to occur.
Q 25 / 25
Burning of magnesium ribbon produces a bright white light due to formation of magnesium oxide.

Frequently Asked Questions

A chemical reaction is a process in which one or more substances change to form new substances with new properties.

A chemical equation is a symbolic representation of a chemical reaction using formulas of reactants and products.

Equations are balanced to satisfy the Law of Conservation of Mass, ensuring equal atoms on both sides.

Reactants are starting substances, and products are the new substances formed in a chemical reaction.

A balanced equation has equal numbers of each type of atom on both sides of the reaction.

It shows the correct formulas of reactants and products but is not balanced.

Common symbols: (s) solid, (l) liquid, (g) gas, (aq) aqueous solution.

A combination reaction occurs when two or more reactants combine to form a single product.

The reaction of hydrogen and oxygen forming water (H2 + ½O2 ? H2O).

A reaction in which a single compound breaks down into two or more simpler substances.

Heating of calcium carbonate gives CaO and CO2 (CaCO3 ? CaO + CO2).

A single element replaces another element from its compound in a reaction.

Two compounds exchange ions to form two new compounds.

Precipitation is a type of double displacement reaction forming an insoluble solid.

Oxidation is the addition of oxygen or removal of hydrogen during a reaction.
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