Punjab Board - Class 12 (PSEB 12th Senior Secondary Board Exam) previous year questions (PYQ)

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Heavy water ($D_2O$) is utilized as a moderator in thermal nuclear power reactors.

Reason (R): Deuterium nuclei slow down energetic fission neutrons through elastic collisions without substantial parasitic neutron absorption.

Refer to the Case Study 'Case Study: Parabolic Cable Geometry in Civil Engineering Suspension Bridges' to answer:

What is the vertical height of the suspension cable at a horizontal distance of $25\text{ m}$ from the bridge center?

English (PSEB Primary / 5th Board): What is the core moral lesson in 'Reproduction in Organisms and Flowering Plants'?

Higher Academic Core: In advanced conceptual study of 'Relations and Functions (Equivalence, Invertible Functions)' in Calculus, Vectors & Probability, which foundational mechanism is universally verified?

Refer to the Case Study 'Case Study: Parabolic Cable Geometry in Civil Engineering Suspension Bridges' to answer:

Determine the parameter $c$ in the parabolic equation $y = ax^2 + c$ from the vertex information.

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Gastric enzyme pepsin requires an acidic environment to digest dietary proteins.

Reason (R): Hydrochloric acid secreted by parietal cells creates optimum pH (1.5 to 2.0) and cleaves inactive pepsinogen into active pepsin.

Directions: In the following question, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Biomagnification of fat-soluble chlorinated pesticides like DDT is highest in top carnivores (fish-eating raptors).

Reason (R): DDT is lipid-soluble, biologically non-degradable, and cannot be metabolized or excreted, accumulating progressively at successive trophic levels.

Refer to the Case Study 'Case Study: Parabolic Cable Geometry in Civil Engineering Suspension Bridges' to answer:

What is the vertical height of the suspension cable at a horizontal distance of $25\text{ m}$ from the bridge center?

Refer to the Case Study 'Case Study: Parabolic Cable Geometry in Civil Engineering Suspension Bridges' to answer:

Determine the parameter $c$ in the parabolic equation $y = ax^2 + c$ from the vertex information.

ਗਣਿਤ ਦੀ ਦੁਨੀਆ (ਪ੍ਰਾਇਮਰੀ / 5ਵੀਂ ਬੋਰਡ): 'Continuity and Differentiability (Chain Rule, Rolle's & Mean Value Theorems)' ਸੰਬੰਧੀ ਸਹੀ ਗਣਨਾ ਜਾਂ ਸੂਤਰ ਕੀ ਹੈ?

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Plant stomata close rapidly under severe soil moisture deficit and drought stress.

Reason (R): Abscisic acid (ABA) synthesized during drought induces potassium and anion efflux from guard cells, causing loss of turgor pressure.

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): The square root of 2 ($\sqrt{2}$) is an irrational real number.

Reason (R): The square root of any positive prime integer is an irrational number.

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Energy flow through ecological food webs is strictly unidirectional.

Reason (R): Solar energy captured by autotrophic producers is dissipated as metabolic heat and cannot revert back to solar radiation, diminishing at successive trophic levels.

Directions: In the question below, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option:

Assertion (A): Gastric enzyme pepsin requires an acidic environment to digest dietary proteins.

Reason (R): Hydrochloric acid secreted by parietal cells creates optimum pH (1.5 to 2.0) and cleaves inactive pepsinogen into active pepsin.