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Speed of sound = 60 m/s Time delay = 4 s (light travel time is negligible) Distance = speed \times time = 60 \times 4 = 240 m

Sound waves are mechanical waves, which means they require a medium to travel through. They can travel through all three states of matter: gases (like air), liquids, and solids.

f = 250 Hz; \lambda = 1.3 m; t = 1 s; d = ? v = f\lambda = 250 \times 1.3 = 325 ms\(^{-1}\) v = \(\frac{2d}{\text{t}}\) ∴ d = \(\frac{v \times t}{2}\) = \(\frac{(325 \times 1)}{2}\) = 162.5 m

Quality (overtones) is a characteristic note of a musical instrument that distinguishes it from another note of the same pitch and loudness produced by another instrument.

\lambda = 1 m; v = 200 ms\(^{-1}\); f = ?; f = \(\frac{\text{v}{ \lambda}\) = \(\frac{200}{1}\) = 200 Hz

Short-sightedness (myopia) means distant objects focus in front of the retina, with the far point at 95 cm. A diverging lens (concave) corrects this by creating a virtual image of distant objects (u = \infty) at the far point (v = -95 cm). Using the lens formula: 1/f = 1/v - 1/u = -1/95 - 0, so f = -95 cm (diverging lens with focal length 95 cm).

B. Ciliary muscle. The ciliary muscles control the shape of the lens, allowing the eye to focus on objects at different distances by changing the focal length of the lens.

The tension \( T \) in a string is defined as the force acting along the string. The dimensional formula for force is given by: \([T] = [F] = [M^1 L^1 T^{-2}]\) Thus, the dimensional symbol of tension in a string is: \([T] = [M L T^{-2}]\)

From Faraday's first law, the mass deposited \( m = Z Q \), where \( Z \) is the electrochemical equivalent and \( Q \) is the charge passed. Since the same charge \( Q \) passes through both voltmeters: \(Q = \frac{m_{\mathrm{Cu}}}{Z_{\mathrm{Cu}}} = \frac{m_{\mathrm{Ag}}}{Z_{\mathrm{Ag}}} \) Rearranging for \( Z_{\mathrm{Ag}} \): \(Z_{\mathrm{Ag}} = \frac{m_{\mathrm{Ag}} \cdot Z_{\mathrm{Cu}}}{m_{\mathrm{Cu}}} \) But: \( m_{\mathrm{Cu}} = 0.2 \, \mathrm{g} \), \( m_{\mathrm{Ag}} = 1.2 \, \mathrm{g} \), \( Z_{\mathrm{Cu}} = 0.00028 \, \mathrm{g \, C^{-1}} \) \(Z_{\mathrm{Ag}} = \frac{1.2 \times 0.00028}{0.2} = \frac{0.000336}{0.2} = 0.00168 \, \mathrm{g \, C^{-1}} \)

Magnesium (Mg) belongs to Group 2 (the Alkaline Earth metals) and Period 3 of the periodic table, meaning it has 2 valence electrons and three electron shells, placing it in the s-block.

The compound [Cu(NH\(_3\))\(_4\)]Cl\(_2\) is an ionic compound composed of a complex cation, the tetraamminecopper(II) ion ([Cu(NH\(_3\))\(_4\)]\(^{2+}\)), and two chloride anions (Cl\(^−\)). The primary force connecting the positively charged complex ion and the negatively charged chloride ions is the electrostatic attraction known as an ionic bond. This bond forms between species with a significant difference in electronegativity, specifically between a cation and an anion. Dative bonds (coordinate covalent bonds) exist within the complex ion itself, specifically between the central copper(II) ion and the nitrogen atoms of the ammonia ligands. Van der Waals forces and typical covalent bonds are not the main attractive forces between the distinct cation and anion units in this solid salt structure. The correct answer is ionic - option C

The commercial deodorant (specifically spray or mist form) is an example of a colloid called an aerosol. In this type of colloid, the dispersed phase (the substance being spread out) is a liquid, while the dispersion medium (the substance the phase is dispersed in) is a gas (air or propellant).

In the reaction given, the chemical reaction can be re-written as A + B → C + D This implies, A and B are the reactants, while C and D are the products. The energy level of the products (C+D) is higher (50) on the graph than the energy level of the reactants (A+B), (20). The arrow representing the overall enthalpy change (\DeltaH) points upward, showing a gain in energy, resulting in a positive \DeltaH value. i.e \DeltaH\(_{reaction}\) = \DeltaH\(_{product}\) - \DeltaH\(_{reactant}\) \DeltaH\(_{reaction}\) = (C+D) - ( A+B) = 50 - 20 = +30 \DeltaH\(_{reaction}\) = + ve , hence, it is an endothermic reaction - option B

Answer: A. Red (Visible spectrum: red ~700 nm, longest; violet ~400 nm, shortest.)

Lens power P = 1/f, where f is focal length in meters; unit is diopter.