Camphor is a waxy, colourless solid with strong aroma that evaporates through the process of sublimation if left in the open at room temperature.
(Cylindrical-shaped Camphor tablets) A cylindrical camphor tablet whose height is equal to its radius (r) evaporates when exposed to air such that the rate of reduction of its volume is proportional to its total surface area. Thus, the differential equation \( \frac{dV}{dt} = -kS \) is the differential equation, where \( V \) is the volume, \( S \) is the surface area, and \( t \) is the time in hours.
Based upon the above information, answer the following questions:
(i) Write the order and degree of the given differential equation.}
(ii) Substituting \( V = \pi r^3 \) and \( S = 2 \pi r^2 \), we get the differential equation \( \frac{dr}{dt} = \frac{2}{3}k \). Solve it, given that \( r(0) = 5 \) mm.}
(iii) (a) If it is given that \( r = 3 \) mm when \( t = 1 \) hour, find the value of \( k \). Hence, find \( t \) for \( r = 0 \) mm.}
(iii) (b) If it is given that \( r = 1 \) mm when \( t = 1 \) hour, find the value of \( k \). Hence, find \( t \) for \( r = 0 \) mm.
Read the following text carefully:
Union Food and Consumer Affairs Minister said that the Central Government has taken many proactive steps in the past few years to control retail prices of food items. He said that the government aims to keep inflation under control without compromising the country’s economic growth. Retail inflation inched up to a three-month high of 5.55% in November 2023 driven by higher food prices. Inflation has been declining since August 2023, when it touched 6.83%. 140 new price monitoring centres had been set up by the Central Government to keep a close watch on wholesale and retail prices of essential commodities. The Government has banned the export of many food items like wheat, broken rice, non-basmati white rice, onions etc. It has also reduced import duties on edible oils and pulses to boost domestic supply and control price rise. On the basis of the given text and common understanding,
answer the following questions: