Everyday Science — Past Papers — Part 5 MCQs with Explanations

The cornea is the transparent, curved outer layer at the front of the eye. It helps focus light entering the eye. It protects the iris, pupil, and other internal parts of the eye. The cornea does not contain blood vessels but has many nerve endings .

The kidney was the first human organ to be successfully transplanted. The first successful living-donor kidney transplant was performed on December 23, 1954 . It was performed by Dr. Joseph Murray and his team in Boston, USA . The transplant was between identical twins, Ronald and Richard Herrick .

A normal human body has one gallbladder . The gallbladder is a small, pear-shaped organ located beneath the liver . It stores and concentrates bile , which helps digest fats. Bile is released into the small intestine during digestion.

Ibn al-Haytham presented the theory of reflection and refraction of light. He is also known as Alhazen. His work, particularly his "Book of Optics", is titled Kitab al-Manazir, written during 1011–1021. Born: c. 965 (c. 354 AH) Basra, Buyid Emirate Died: c. 1040 (c. 430 AH)[1] (aged around 75 ) Cairo, Fatimid Caliphate

The term “ antigen ” was coined in 1899 by Ladislas Deutsch (László Detre). The word is derived from “ antibody-generating ” (anti + gen). Additional information : Louis Pasteur is famous for his work on vaccination and germ theory . Edward Jenner pioneered the smallpox vaccine .

Phosphorus is not among the top 10 most abundant elements in the Earth's crust. Most abundant element in Earth crust is Oxygen . Oxygen in the crust is ( 46. 1% ). The chemical formula of oxygen ( dioxygen ) is O2 . List of 10 Most Abundant Elements in the Earth's Crust: Sr# Element Abundance percent by weight 1 Oxygen 46.10% 2 Silicon 28.20% 3 Aluminum 8.23% 4 Iron 5.63% 5 Calcium 4.15% 6 Sodium 2.36% 7 Magnesium 2.33% 8 Potassium 2.09% 9 Titanium 0.57% 10 Hydrogen 0.14%

The main reaction occurring in the Sun's core is nuclear fusion . In fusion, hydrogen nuclei combine to form helium , releasing a huge amount of energy. This energy is responsible for the Sun's light and heat . The Sun's primary fusion process is the proton–proton chain reaction.

Deuteranopia is a type of red-green colour blindness caused by the absence of functioning green-sensitive cones. It mainly affects the ability to distinguish green from red . It is an X-linked recessive condition. It is more common in males .

Latent heat of fusion is the heat required to c hange ice into water at 0°C. For ice, it is approximately 80 cal/g. In SI units, it is about 334 J/g. During melting, the temperature remains constant. The heat is used to change the state of matter, not raise its temperature .

Pressure is a scalar quantity. Pressure can be defined as the force acting per unit area. The unit of pressure is N/m² (Newton per square meter). It is also called a pascal (Pa). In SI base units : kg⋅m−1⋅s−2 Derivation from other quantities: p = F / A Dimensional unit: M L^−1 T^-2 .

Boyle’s Law states that pressure and volume are inversely proportiona l. It applies when temperature remains constant . Formula: P∝ 1/v Therefore, P V = constant If volume decreases, pressure increases, and vice versa.

Phase change: Ice turns from a solid into a liquid. Melting point: The constant temperature at which this change happens is 0 degrees Celsius (32 degrees Fahrenheit) Heat absorption: Ice takes in heat energy to break its rigid crystal structure Constant temperature: The temperature stays at 0 °C until all the ice melts.

Aluminium is more reactive than silver. Aluminium forms very stable compounds with oxygen. Therefore, it requires electrolysis for extraction . Silver is less reactive and is easier to extract from its ores. Hence, aluminium extraction is more difficult than silver extraction.

The sum of the powers (exponents) of reactant concentrations in the rate law gives the reaction order. For example: Rate = k[A]^2[B] Overall order = 2 + 1 = 3. Reaction order shows how the rate depends on concentration. It is determined experimentally, no t directly from the balanced chemical equation.

The nucleus is the central core of an atom. It contains protons and neutrons . Protons have a positive charge. Neutrons have no charge. Electrons move around the nucleus.

Ammonia is produced by the Haber process. The reaction is: N₂ + 3H₂ ⇌ 2NH₃. There are 4 moles of gas on the left and 2 moles on the right . Increasing pressur e shifts the equilibrium toward ammonia. Therefore , higher pressure increases ammonia production.

Crystallography is the branch of science devoted to the study o f molecular and crystalline structure and properties. Tools: Scientists use techniques like X-ray diffraction to see these hidden patterns . Applications: It helps us understand minerals, metals, and medicines like proteins .

The particle's path is a helix . Reasoning: Velocity has two components: Parallel to the fields → electric force accelerates it along the axis Perpendicular to the fields → magnetic force makes it circle around the axis Combined → helical path (with changing pitch as it speeds up/slows down)

Length, mass, and time are fundamental physical quantities. They can be measured using standard units . SI units are the metre for length, the kilogram for mass, and the second for time.

Formula: Mean = Sum of observations / Number of observations Given: Mean = 50 Number of observations = 10 Sum of observations = Mean _ Number of observations = 50 _ 10 = 500

Given ratio = Nitrogen : Sulphur : Phosphorus = 5 : 3 : 2 Total parts = 5 + 3 + 2 = 10 Total weight = 200 kg Value of 1 part = Total weight / Total parts = 200 / 10 = 20 kg Initial weight of Nitrogen = 5 x 20 = 100 kg Initial weight of Sulphur = 3 x 20 = 60 kg Initial weight of Phosphorus = 2 x 20 = 40 kg 100 kg of Nitrogen is added. New weight of Nitrogen = 100 + 100 = 200 kg Verified & Updated

Humidity is the measure of the amount of moisture (water vapour) in the air. A hygrometer is used to measure relative humidity . A psychrometer is an example of a hygrometer . Relative humidity tells us the ratio of water vapour present in the air compared with the maximum amount the air can hold at a given temperature . Humidity is commonly expressed as a percentage (%).

Venus comes closest to Earth when it is between Earth and the Sun . Minimum distance: about 24 million miles (≈ 38 million km) . This close approach occurs roughly every 584 days . Additional Information : Mercury can be about 33 million miles away when Venus is on the far side of the Sun.

Albuminurophobia is a fear of kidney disease . The term is associated with an excessive or irrational fear of developing kidney disease . Albuminuria refers to the presence of albumin (a protein ) in urine. The term is related to concerns about kidney health and disease .

Given: Diameter, d = 19 mm = 0.019 m Length, L = 1.51 m Tensile force, P = 150 k N = 150 , 000 N Modulus of Elasticity, E = 200 GP a = 200 × 1 0 9 N / m^ 2 Formula: δ = P L/ A E ​ 1. Cross-sectional area: A = π d^ 2 ​/4 A = π ( 0.019 )^ 2/4 ​ = 0.0002835 m^ 2 2. Axial elongation: δ = 150000 × 1.51/ 0.0002835 × 200 × 1 0^ 9 δ = 0.003994 m δ = 3.99 mm Answer: 3.99 mm ≈ 4 mm ​

Earthquakes generate dynamic/inertial forces in a dam. These forces can significantly increase the shear stress within the dam . Earthquake loading is therefore considered in the seismic design of dams .

Hydrostatic pressure is the pressure exerted by a fluid when it is at rest . It increases with the depth of water . The basic formula is: P = ρgh Here, ρ = density of water, g = acceleration due to gravity, and h = depth. It is important in the design of dams, tanks, reservoirs, and retaining structures.

Soil with a particle size less than 0.002 mm and high cohesion is called clay . It feels sticky when wet, holds a lot of water, and hardens when dry .

The strength of clay is mainly due to cohesion Why Clay Has High Cohesion Tiny particles: Clay particles are microscopic and flat, like tiny plates. Water films: Water molecules stick between these tiny plates. Electrostatic forces: Strong electrical charges pull the particles close to each other.

Depression is classified as a psychological and medical mood disorder It disrupts normal work and social life. Low mood or ongoing sadness Loss of pleasure in hobbies . Changes in sleep or weight

Paleolithic = Old Stone Age; people hunted animals and gathered wild plants. "Old Stone Age," the earliest and longest human era ( roughly 2.6 million years ago to about 10,000 BCE ).

Sandra Harding Developed feminist epistemology; identified three approaches : Feminist empiricism (1986, The Science Question in Feminism ) Standpoint theory (1991, Whose Science? Whose Knowledge?) Postmodern feminism (1986, later works) Additional information Simone de Beauvoir — The Second Sex (1949) Judith Butler — Gender Trouble (1990) Betty Friedan — T he Feminine Mystique (1963)

The Chalcolithic Period (also called the Copper Age): Marks the transition between the Stone Age and the Bronze Age Defined by the simultaneous use of stone and copper tools Name comes from the Greek chalcos (copper) and lithos (stone) It's the period when humans first began working with metal

A series of steps is called a staircase, stairway, or a flight of stairs Additional information: Tread: The flat, horizontal top surface where you place your foot. Riser: The vertical part that forms the gap between one step and the next . Nosing: The front, rounded edge of the tread that sticks out over the riser Last updated 14 August 2026 by NA

Cast iron pipes are strong and durable. They are mainly used for underground water-supply lines. They can withstand high water pressure. They have a long service life. They are suitable for large and permanent water-supply systems

Plain Sedimentation (4–8 hours): Relies purely on gravity for natural particle settling. Coagulation-Sedimentation (2–4 hours): Uses chemical coagulants to accelerate particle clumping and settling. Detention Time Formula: Calculated as (T =V/Q), dividing tank volume (V) by flow rate (Q) [KETOS].

Traditional walking sticks are commonly made of wood. Wood is strong and durable. Last updated 13 August 2026 by NA

Oxygen reacts with most elements to produce binary compounds called oxides . An oxide is a compound formed when oxygen combines with another element. Oxides may be metallic or non-metallic depending on the element involved. Examples include CO₂ (carbon dioxide), MgO (magnesium oxide), and Fe₂O₃ (iron oxide). Oxides can have acidic, basic, or amphoteric properties.

Water (H₂O) and carbon dioxide (CO₂) combine to form carbonic acid (H₂CO₃). The reaction is: CO₂ + H₂O ⇌ H₂CO₃. Carbonic acid is a weak acid . It forms naturally when CO₂ dissolves in water. Carbonic acid contributes to the slightly acidic nature of rainwater.

First man who travelled in Space was Yuri Gagarin in 1961. Yuri Gagarin was a Soviet pilot and cosmonaut. He aboard the first successful crewed spaceflight, became the first human to journey into outer space. Additional information : First man who Walk in Space was Alexei Leonov in 1965. First man who Walk on Moon was Neil Armstrong in 1969.