Class X Science Exam

Hydrogen gas reacts with nitrogen gas to produce ammonia gas. The balanced chemical equation represents the stoichiometry of the reaction, ensuring that the number of atoms of each element on the reactant side equals the number on the product side.

A chemical equation represents a chemical reaction in a symbolic form. It shows the chemical formulas of the reactants and products, and their stoichiometric coefficients, which indicate the relative amounts of each substance involved.

Represents the number of molecules or moles of a substance involved in the reaction. They are used to balance chemical equations, ensuring that the number of atoms of each element on the reactant side equals the number on the product side. They act as multiplies of the molecules or moles they are referring to.

The reactants are the substances that are present at the start of a chemical reaction, and they are written on the left side of the chemical equation.

The products are the substances that are formed as a result of a chemical reaction, and they are written on the right side of the chemical equation.

An acid with the highest hydronium ion concentration is the strongest acid.

The transport of soluble products of photosynthesis (sugars) from the leaves to other parts of the plant is called translocation.

A reaction that produces heat is known as an exothermic reaction.

A chemical reaction that absorbs heat from the surroundings is known as an endothermic reaction.

The solution turning red indicates that the solution is acidic.

A white precipitate forming indicates that a chemical reaction has occurred, where an insoluble solid is produced.

A yellow precipitate forming indicates that a chemical reaction has occurred, and an insoluble solid of a particular color is produced.

A chemical reaction where heat is released into the surroundings is known as an exothermic reaction.

The magnification produced by a rear-view mirror fitted in vehicles is always less than one, making objects appear smaller than they actually are.

The inner lining of the stomach is protected from the corrosive hydrochloric acid by a layer of mucus secreted by the stomach lining cells.

The velocity of light in glass is less than the velocity of light in vacuum.

The components of phloem tissue involved in transporting food in plants are sieve tubes (long, thin cells that form a continuous tube) and companion cells (which provide nutrients and energy to the sieve tubes).

Sodium hydrogen carbonate (NaHCO3), commonly known as baking soda, neutralizes excess stomach acid, relieving heartburn and indigestion.

Sodium hydrogen carbonate reacts with acids in the stomach to form carbon dioxide gas, which is released as burps, providing relief.

The reaction between sodium hydrogen carbonate and stomach acid releases heat, which aids in neutralizing the acidic environment.

Sodium hydrogen carbonate helps neutralize the acidic environment in the stomach, providing relief from heartburn and indigestion.

The focal length of a convex lens is the distance between the optical center of the lens and the principal focus.

The focal length of the convex lens can be determined by observing the image distance when the object distance is very large. In the table, as the object distance increases, the image distance approaches a constant value. This constant value represents the focal length of the lens.

The image distance (v) is not correct for the object distance (u) where the image distance is negative. This indicates that a real image is formed in this case, but it contradicts the observation that a convex lens typically forms virtual images for very large distances.

A convex lens typically forms virtual images when the object is placed very far away. However, in this observation data, the image distance is negative for a particular object distance. This means the lens is forming a real image, which is not consistent with its usual behavior.

In the table, the image distance (v) is given as 'Infinity'. When the object is placed at the focal point of a convex lens, the rays of light emerge parallel to each other, making the image form at infinity.

The heart is a muscular organ that pumps blood throughout the body. It is located in the thoracic cavity, between the lungs, and above the diaphragm.

Valves in the heart are flaps of tissue that prevent blood from flowing backward. They ensure that blood flows in one direction through the heart.

Ventricles have thicker walls than atria because they are responsible for pumping blood out of the heart with more force. The atria only need to pump blood a short distance to the ventricles.

1M HCl has a higher concentration of hydrogen ions (H+) than 1M CH3COOH. This is because HCl is a strong acid, meaning it dissociates completely in water, releasing all its hydrogen ions. CH3COOH is a weak acid, meaning it only partially dissociates, releasing fewer hydrogen ions.

Strong acids ionize completely in water, meaning they release all of their hydrogen ions (H+). This results in a higher concentration of H+ ions in the solution.

Weak acids only partially ionize in water, meaning they do not release all of their hydrogen ions (H+). This results in a lower concentration of H+ ions in the solution compared to strong acids.

The concentration of hydrogen ions (H+) in a solution determines its acidity. Higher H+ concentration means the solution is more acidic.

The heart is responsible for pumping blood throughout the body. It receives deoxygenated blood from the veins and pumps oxygenated blood to the arteries.