Test :- Chemical Reactions And Equations Class –10 - Class 10 MCQ

i) Chemical digestion involves the secretions of enzymes throughout your digestive tract. These enzymes break the chemical bonds that hold food particles together. This allows food to be broken down into small, digestible parts.

ii) As no chemical bonds are broken, and no new substances are formed when sugar is dissolved in water so, it is not a chemical reaction.

iii) Chemical changes require a change on a molecular level that cannot be reversed because they form some new substance. Souring milk is not something you can reverse, and the process of it souring produces new molecules.

iv) All the light a candle makes comes from a chemical reaction known as combustion in which the wax (made from carbon-based chemicals typically derived from petroleum) reacts with oxygen in the air to make a colorless gas called carbon dioxide.

A chemical reaction in which electrons are transferred between two reactants participating in it. This transfer of electrons can be identified by observing the changes in the oxidation states of the reacting species.

Galvanisation or galvanization (or galvanizing as it is most commonly called) is the process of applying a protective zinc coating to iron or steel, to prevent rusting.

Rancidity refers to the spoilage of a food in such a way that it becomes undesirable (and usually unsafe) for consumption.

After balancing the equation:

Na₂CO₃ + 2HCl → 2NaCl + CO₂ + H₂O.

hence, x=2

When copper is heated in the presence of air in a very high temperature,a chemical reaction takes place. In this situation,the highly heated copper reacts with the oxygen of the air to form a thin layer of copper oxide on the surface of metallic copper

Magnesium is displacing copper

Chlorine is often used as an oxidizing chemical to convert hydrogen sulfide gas to insoluble sulfur (a yellow solid).

i) Aluminium metal will react with dilute hydrochloric acid to produce aqueous aluminium chloride, AlCl₃ , and hydrogen gas, H₂.

ii) The reaction between magnesium (Mg) and hydrochloric acid (HCl) combine to form a salt of magnesium chloride (MgCl) and release hydrogen gas (H₂​).This is a single replacement reaction.

iii) Copper is a very unreactive metal, and it does not react with hydrochloric acid. Hydrogen is above copper in a metal reactivity series, so copper cannot replace the hydrogen in HCl to form CuCl₂

iv) Zinc reacts with hydrochloric acid to produce hydrogen gas because it's more reactive than hydrogen, and thus displaces the latter from an acid. By comparison