| List-I | List II | ||
|---|---|---|---|
| A. | Phenol-formaldehyde resin | I | Glyptal |
| B. | The copolymer of 1,3-butadiene and styrene | II | Novolac |
| C. | Polyester of glycol and phthalic acid | III | Buna-S |
| D. | Polyester of glycol and terephthalic acid | IV | Dacron |
To solve this matching question, we need to understand the properties and common applications of each type of polymer mentioned. Let's match List-I with List-II using our knowledge of these substances:
Based on the matches above, the correct option is: A-II, B-III, C-I, D-IV.
In the given figure, the blocks $A$, $B$ and $C$ weigh $4\,\text{kg}$, $6\,\text{kg}$ and $8\,\text{kg}$ respectively. The coefficient of sliding friction between any two surfaces is $0.5$. The force $\vec{F}$ required to slide the block $C$ with constant speed is ___ N.
(Given: $g = 10\,\text{m s}^{-2}$) 
Two circular discs of radius \(10\) cm each are joined at their centres by a rod, as shown in the figure. The length of the rod is \(30\) cm and its mass is \(600\) g. The mass of each disc is also \(600\) g. If the applied torque between the two discs is \(43\times10^{-7}\) dyne·cm, then the angular acceleration of the system about the given axis \(AB\) is ________ rad s\(^{-2}\).

Neoprene is formed from chloroprene. It is prepared by free radical polymerisation. The monomer of neoprene is chloroprene. It is used for preparing gaskets, conveyor belts etc.