AP TET Paper 2 Math and Science Model Paper 4

Concept:Alkanes are saturated hydrocarbons containing only single bonds between carbon atoms.Explanation:The general formula of alkanes is $C_{n}H_{2n+2}$, where $n$ is the number of carbon atoms.Each carbon atom forms four single covalent bonds, and the remaining valencies are satisfied by hydrogen atoms.For $n$ carbon atoms, the number of hydrogen atoms is $2n+2$.For example, methane has $n = 1$, so $H = 2(1) + 2 = 4$, giving $\mathrm{CH_4}$.Ethane has $n = 2$, so $H = 2(2) + 2 = 6$, giving $\mathrm{C_2H_6}$.Propane has $n = 3$, so $H = 2(3) + 2 = 8$, giving $\mathrm{C_3H_8}$.These examples confirm that the formula $C_{n}H_{2n+2}$ holds for all alkanes.Answer:A. $C_{n}H_{2n+2}$