Объяснение:
CH3-CH2-CH2OH -> CH3-CH=CH2 -> CH3-CHCl-CH3 -> CH3-CH=CH2
1) CH3-CH2-CH2OH =(H2SO4, t)=> CH3-CH=CH2 + H2O - 3
2) CH3-CH=CH2 + HCl => CH3-CHCl-CH3 - 4
3) CH3-CHCl-CH3 + NaOH =(спирт, t)=> CH3-CH=CH2 + NaCl + H2O - 2
ответ: 342