Primary alkyl halide vs vs methyl halide sn2 speed

[MaizeGoBlue]

So this question asks alkyl halide would be the most suitable for an SN2 reaction and then lists methyl chloride, 1-chloropropane, a secondary halide, and two tertiary halides. I know it can't be the secondary or tertiary halides due to steric hindrance, so that leaves me with methyl chloride vs 1-chloropropane. How do I decide between these two? Is there something I'm missing where chain length affects hindrance?

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[jz123]

If you can draw out the structure of methyl chloride, the answer is there. I think you just mis-interpreted the structure of methyl chloride; it is a chloride bound to a methyl group.
Having 3 hydrogens is less steric than having 2 hydrogen and a carbon nearby, so methyl chloride is better 1 chloroproane for SN2 reactions. Hope this helps. Correct me if I am wrong.

 

[DAT Destroyer]

So this question asks alkyl halide would be the most suitable for an SN2 reaction and then lists methyl chloride, 1-chloropropane, a secondary halide, and two tertiary halides. I know it can't be the secondary or tertiary halides due to steric hindrance, so that leaves me with methyl chloride vs 1-chloropropane. How do I decide between these two? Is there something I'm missing where chain length affects hindrance?

The less carbons you have, the faster it can undergo Sn2 reaction. Therefore Methyl chloride does Sn2 faster than propyl chloride due to less steric hindrance.

Hope this helps.