1.
(b) Brown
Reason: Ferrous sulphate crystals (\(FeSO_4 \cdot 7H_2O\)) lose water to become white. On heating, they
decompose to form Ferric Oxide (\(Fe_2O_3\)) which is reddish-brown, releasing \(SO_2\)
and \(SO_3\).
2.
(a) (i) and (ii)
Reason: In \(2PbO + C \rightarrow 2Pb + CO_2\): Lead Oxide (PbO) is reduced (loses oxygen), and Carbon
(C) is oxidised (gains oxygen). Statements saying Lead is reduced and CO2 is oxidised are incorrect.
3.
(b) Catenation
Reason: Catenation is the self-linking property of carbon atoms to form long chains, branches, and
rings.
4.
(d) Small intestine
Reason: Digestion of carbohydrates, proteins, and fats is completed here by intestinal and pancreatic
enzymes.
5.
(d) Phototropism
Reason: Movement of a plant part in response to light is called phototropism.
6.
(d) Tallness is the dominant trait.
Reason: In the F1 generation of a monohybrid cross, only the dominant trait is expressed.
7.
(c) At the centre of curvature
Reason: A concave mirror forms a real, inverted, and same-sized image only when the object is at 'C'.
8.
(c) Ciliary muscles
Reason: They modify the curvature of the eye lens, changing its focal length (Accommodation).
9.
(a) 1 A
Reason: In a series circuit, the current flowing through all components is the same.
10.
(c) Originate from the North pole and end at its South pole.
Reason: Magnetic field lines emerge from North and merge at South outside the magnet.
11.
(b) Decomposition of calcium carbonate
Reason: Thermal decomposition requires heat absorption (Endothermic). Others are exothermic.
12.
(d) (i) and (iv)
Reason: Asexual reproduction is uniparental and gamete-free, leading to genetically identical clones.
13.
(d) They are made of non-biodegradable materials.
Reason: Plastics persist in the environment and cause pollution.
14.
(b) Red
Reason: Red light has the longest wavelength and bends (deviates) the least.
15.
(d) \(2 \Omega\)
Calculation: \(1/R_{eq} = 1/6 + 1/6 + 1/6 = 3/6\). \(R_{eq} = 6/3 = 2 \Omega\).
16.
(d) The magnetic field decreases if the current is increased.
Reason: False. Magnetic field strength \(B\) is directly proportional to current \(I\).
17.
(a) Both A and R are true and R is correct explanation of A.
Reason: Amphoteric oxides react with both acids and bases.
18.
(a) Both A and R are true and R is correct explanation of A.
Reason: Phloem translocation is an active process utilizing ATP energy.
19.
(c) A is true, R is false.
Reason: Myopia is corrected with a Concave lens.
20.
(c) A is true, R is false.
Reason: The white gene is present but recessive (masked), so it is passed on.
21.
(a) Earth Wire: Protects users from electric shock by providing a low-resistance path for
leakage current to the ground.
(b) Fuse Wire: Protects appliances/circuits by melting and breaking the connection when
current exceeds safe limits.
22.
In space, there is no atmosphere (no particles) to scatter light. Without scattering, no
light reaches the astronaut's eyes from the sky, making it appear black.
23.
(a) Pepsin: Enzyme in stomach that digests proteins into smaller peptides (works in acidic
medium).
(b) Villi: Finger-like projections in the small intestine that increase surface area for
rapid absorption.
24.
Location: Flower.
Male: Stamen (Anther, Filament).
Female: Pistil (Stigma, Style, Ovary).
25.
(a) Exothermic: Because energy (ATP/heat) is released during the breakdown of glucose.
(b) \(C_6H_{12}O_6(aq) + 6O_2(g) \rightarrow 6CO_2(g) + 6H_2O(l) + Energy\)
26.
(a) \(N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)\)
(b) \(2K(s) + 2H_2O(l) \rightarrow 2KOH(aq) + H_2(g) + Heat\)
27.
NaCl: Na (2,8,1) loses 1e- to Cl (2,8,7). Forms \(Na^+\) and \(Cl^-\). Held by
electrostatic force.
MgCl2: Mg (2,8,2) loses 2e-. Two Cl atoms gain 1e- each.
Forms \(Mg^{2+}\) and \(2Cl^-\).
28.
(a) Functional Group: An atom/group determining chemical properties. (i) Ketone (ii)
Carboxylic Acid.
(b) Hexanal: \(CH_3-CH_2-CH_2-CH_2-CH_2-CHO\) (Aldehyde group at end).
29.
(a) Flow: Body \(\rightarrow\) Vena Cava \(\rightarrow\) Right Atrium \(\rightarrow\) Right
Ventricle \(\rightarrow\) Lungs \(\rightarrow\) Left Atrium \(\rightarrow\) Left Ventricle \(\rightarrow\)
Aorta \(\rightarrow\) Body.
(b) Reason: High energy requirement for body temperature regulation in birds/mammals
necessitates separation for efficient oxygen supply.
30.
(a) Pathway: Light \(\rightarrow\) Retina \(\rightarrow\) Sensory Neuron \(\rightarrow\)
Brain \(\rightarrow\) Motor Neuron \(\rightarrow\) Iris Muscles \(\rightarrow\) Pupil constricts.
(b) Receptor: Retina. Effector: Iris muscles.
31.
Real, inverted, same size image means object is at 2F.
\(v = 50\) cm. Since \(v=2f\), \(f = 25\) cm (\(0.25\) m).
Object distance \(u = 50\) cm.
Power: \(P = 1/f(m) = 1/0.25 = +4\) Dioptre.
32.
(a) Joule's Law: \(H = I^2Rt\).
(b) Rate (Power): \(P = I^2R = 15^2 \times 8 = 225 \times 8 = 1800\) Watts.
33.
(a) Length, Area, Material, Temperature.
(b) Alloys have higher resistivity and do not oxidize (burn) easily at high temperatures.
34.
(a) Roasting: Sulphide ores, excess air. Calcination: Carbonate ores,
limited air.
(b) Extraction: Roast \(Cu_2S\). Then auto-reduction: \(2Cu_2O + Cu_2S \rightarrow 6Cu +
SO_2\).
(c) Refining: Anode: Impure Cu. Cathode: Pure Cu. Electrolyte: Acidified \(CuSO_4\).
35.
(a) Diagram: Female Reproductive System.
(b) (i) Ovary: Eggs/Hormones. (ii) Oviduct: Fertilization site. (iii)
Uterus: Implantation.
(c) Placenta: Provides nutrition/oxygen to fetus and removes waste.
36.
(a) (i) Between P & F: Virtual, Erect, Magnified. (ii) At C: Real,
Inverted, Same Size.
(b) Proof: \(1/v = 1/f - 1/u\). Since \(f\) and \(u\) are negative, and \(u > f\),
calculation shows \(v\) is negative (Real) and \(m\) is negative (Inverted).
37.
(i) 7.0 - 7.8.
(ii) 5.6.
(iii) (a) Pink: Basic solution (pH > 7). E.g., NaOH.
(iii) (b) Baking soda alone creates bitter \(Na_2CO_3\). Tartaric acid neutralizes it.
38.
(i) Bowman's Capsule.
(ii) Urea.
(iii) (a) Glomerulus: Filters blood under high pressure (Ultrafiltration).
(iii) (b) Hemodialysis: Artificial kidney for removing nitrogenous waste via diffusion.
39.
(i) Parallel straight lines (Uniform).
(ii) Right-Hand Thumb Rule.
(iii) (a) Field strength increases; becomes an Electromagnet.
(iii) (b) Solenoid is temporary/adjustable; Bar magnet is permanent.