SZF IOS 2021 previous year paper practice · PYQ-pattern set

SZF IOS 2021 PYQ-pattern questions

Showing 10 of the 20 PYQ-pattern questions in this set — freshly worded in that year's pattern, not the original questions. Answers and solutions open under each question.

1. Q1 · Sound

   A sound wave travels in air at 340 m/s. If the frequency of the sound is 170 Hz, what is the wavelength of the sound wave?

   • A. 1 m
   • B. 2 m
   • C. 3 m
   • D. 4 m
   Answer and solution

   Answer: B

   Using v = fλ, wavelength λ = v/f = 340/170 = 2 m.

2. Q2 · Work, Energy and Power

   A force of 20 N displaces an object by 5 m at an angle of 60° to the direction of force. How much work is done?

   • A. 50 J
   • B. 100 J
   • C. 75 J
   • D. 86.6 J
   Answer and solution

   Answer: A

   Work W = F × s × cos θ = 20 × 5 × cos 60° = 20 × 5 × 0.5 = 50 J.

3. Q3 · Atoms and Molecules

   Calculate the number of molecules present in 8.8 g of carbon dioxide (CO₂). [Given: Atomic mass of C = 12 u, O = 16 u, Avogadro's number = 6.022 × 10²³]

   • A. 1.2 × 10²³ molecules
   • B. 6.022 × 10²³ molecules
   • C. 3.011 × 10²³ molecules
   • D. 1.2 × 10²² molecules
   Answer and solution

   Answer: A

   Molar mass of CO₂ = 12 + 2(16) = 44 g/mol. Number of moles = 8.8/44 = 0.2 mol. Number of molecules = 0.2 × 6.022 × 10²³ = 1.2 × 10²³ molecules.

4. Q4 · Sources of Energy

   Solar panels convert solar energy into electrical energy. What is the main component used in solar panels for this conversion?

   • A. Silicon cells
   • B. Copper coils
   • C. Carbon rods
   • D. Aluminum sheets
   Answer and solution

   Answer: A

   Silicon cells (photovoltaic cells) are the main components in solar panels that convert solar energy directly into electrical energy through the photovoltaic effect.

5. Q5 · Diversity in Living Organisms

   An organism has a notochord present throughout its life, lacks a vertebral column, and shows bilateral symmetry. To which phylum does it belong?

   • A. Arthropoda
   • B. Chordata
   • C. Echinodermata
   • D. Mollusca
   Answer and solution

   Answer: B

   The organism belongs to Phylum Chordata (specifically Protochordata subphylum) as it has a notochord but lacks a vertebral column, distinguishing it from vertebrates.

6. Q6 · Carbon and its Compounds

   Ethanoic acid reacts with sodium hydroxide to form a salt and water. What is the name of this type of reaction?

   • A. Addition reaction
   • B. Neutralization reaction
   • C. Substitution reaction
   • D. Esterification reaction
   Answer and solution

   Answer: B

   The reaction between ethanoic acid (an acid) and sodium hydroxide (a base) to form sodium ethanoate (salt) and water is a neutralization reaction.

7. Q7 · Heredity and Evolution

   A pea plant heterozygous for both height (Tt) and seed color (Yy) is crossed with another plant of the same genotype. What fraction of the offspring will be tall with yellow seeds?

   • A. 1/16
   • B. 3/16
   • C. 9/16
   • D. 12/16
   Answer and solution

   Answer: C

   Using a dihybrid cross (TtYy × TtYy), the phenotypic ratio is 9:3:3:1, where 9/16 offspring will be tall with yellow seeds (both dominant traits).

8. Q8 · Verbal Reasoning

   Choose the word that is most opposite in meaning to 'BENEVOLENT'.

   • A. Generous
   • B. Malevolent
   • C. Kind
   • D. Charitable
   Answer and solution

   Answer: B

   Benevolent means kind and well-meaning. The opposite is malevolent, which means having or showing ill will or evil intentions.

9. Q9 · Experimental and Lab-based

   In an experiment to test the effect of fertilizer on plant growth, a student uses three identical pots with the same soil and plants. Pot A receives no fertilizer, Pot B receives 5g fertilizer, and Pot C receives 10g fertilizer. All pots are placed in different locations with varying light. What is the major flaw in this experimental design?

   • A. The pots should have different types of soil
   • B. Light conditions are not controlled as a variable
   • C. More than three pots should be used
   • D. The fertilizer amounts are too small to measure
   Answer and solution

   Answer: B

   To properly test fertilizer effects, all other variables (especially light) must remain constant. Varying light locations introduces a confounding variable that makes it impossible to isolate fertilizer's true effect.

10. Q10 · Contemporary Science

    Recent studies show that vertical farming in cities uses 95% less water than traditional farming while producing crops year-round. What is the primary advantage of this technology for urban areas?

    • A. It completely eliminates the need for sunlight
    • B. It reduces transportation costs and provides fresh local produce
    • C. It uses more land area than traditional farms
    • D. It requires no electricity for operation
    Answer and solution

    Answer: B

    Vertical farms in cities reduce the distance food travels from farm to consumer, lowering transportation costs and carbon emissions while ensuring fresher produce for urban populations.