This physics problem tests your understanding of fundamental physical laws and their applications. The step-by-step solution below breaks down the problem using relevant equations and physical reasoning.
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Q1d. Explain the following observation: (A) Lightening is seen before the thunder is heard. Light travels at an extremely high speed (3 × 10^8 m/s), while sound travels much slower (approximately 343 m/s in air). Therefore, the light from a lightning strike reaches our eyes almost instantaneously, but the sound (thunder) takes a noticeable amount of time to travel the same distance to our ears. (B) A boy holding a long metal rod with one end in fire feels a burning sensation in the palm. Metals are excellent thermal conductors. When one end of the metal rod is heated in the fire, the heat energy is efficiently transferred along the rod by conduction from the hotter end to the cooler end (the boy's palm). This transfer of thermal energy causes the burning sensation. (C) A clinical thermometer breaks when used to measure the temperature of boiling water. A clinical thermometer is specifically designed to measure human body temperature, typically having a narrow range of about 35^ C to 42^ C. Boiling water is at 100^ C. When exposed to such a high temperature, the liquid inside the thermometer (usually mercury or alcohol) expands excessively beyond the thermometer's calibrated range, causing the glass tube to shatter due to the immense pressure. Q1e. Name the two methods of making magnets. • Stroking method • Electrical method (Electromagnetism) Q3a. Name the planting material used in the propagation of each of the following crops: (i) Plantain: Suckers (ii) Banana: Suckers (iii) Yam: Setts (or tubers) (iv) Cassava: Stem cuttings Q3b. (i) In a laboratory experiment, a student was required to prepare 500 cm³ of 0.1 M solution of glucose (C₆H₁₂O₆). Calculate mass of the glucose the boy need. [C=12, H=1, O=16] Step 1: Calculate the molar mass of glucose (C_6H_12O_6). M_r(C_6H_12O_6) = (6 × 12) + (12 × 1) + (6 × 16) M_r(C_6H_12O_6) = 72 + 12 + 96 M_r(C_6H_12O_6) = 180 g/mol Step 2: Convert the volume from cm³ to dm³. V = 500 cm^3 = (500)/(1000) dm^3 = 0.5 dm^3 Step 3: Calculate the number of moles of glucose needed. n = Molarity × Volume n = 0.1 mol/dm^3 × 0.5 dm^3 n = 0.05 mol Step 4: Calculate the mass of glucose needed. Mass = n × M_r Mass = 0.05 mol × 180 g/mol Mass = 9 g The mass of glucose needed is 9 g. (ii) Give two conditions necessary for rusting. • Oxygen (or air) • Water (or moisture) (iii) State two ways of preventing rusting. • Painting (creates a barrier to oxygen and water) • Oiling/Greasing (creates a protective layer) • Galvanizing (coating with zinc) Q3c. List two examples of specialized cells multicellular organisms and state their function each. • Red blood cells (Erythrocytes): Their primary function is to transport oxygen from the lungs to the body tissues and carbon dioxide from the tissues back to the lungs. They are biconcave discs and lack a nucleus to maximize oxygen-carrying capacity. • Nerve cells (Neurons): Their function is to transmit electrical signals (nerve impulses) throughout the body, enabling communication and coordination between different parts of the organism. They have long extensions (axons and dendrites) for efficient signal transmission.