Arrange CH3F, CHI, CH3Br and CH3Cl in order of their reactivity in nucleophilic substitution reaction.
Give one chemical test to distinguish between C2H5Br and C6H5Br.
Hydrolysis of C2H5Br with refluxing aqueous KOH followed by acidification with dil HNO3 and subsequent treatment with AgNO3 gives light yellow ppt. of AgBr whereas C6H5Br does not gives this test.