Reason R is true: Foam insulation reduces heat transfer due to the presence of air pockets which are poor conductors of heat. However, Assertion A is false. Foam insulation is used to keep the room *cooler* during summer and warmer during winter by acting as a heat insulator.
Three conductors of same length having thermal conductivity \(k_1\), \(k_2\), and \(k_3\) are connected as shown in figure. Area of cross sections of 1st and 2nd conductor are same and for 3rd conductor it is double of the 1st conductor. The temperatures are given in the figure. In steady state condition, the value of θ is ________ °C. (Given: \(k_1\) = 60 Js⁻¹m⁻¹K⁻¹,\(k_2\) = 120 Js⁻¹m⁻¹K⁻¹, \(k_3\) = 135 Js⁻¹m⁻¹K⁻¹)
The following diagram shown restriction sites in E. coli cloning vector pBR322. Find the role of ‘X’ and ‘Y’gens :